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Cristina Giacoma - One of the best experts on this subject based on the ideXlab platform.
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sex and age specific survival and life expectancy in a free ranging population of Indri Indri gmelin 1788
The European Zoological Journal, 2021Co-Authors: F Rolle, Cristina Giacoma, Valeria Torti, Daria Valente, C De Gregorio, A Von HardenbergAbstract:The critically endangered Indri (Indri Indri) is the largest extant lemur species and its population size is projected to decline over the next three generations due to habitat loss, hunting and cl...
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Linguistic laws of brevity: conformity in Indri Indri
Animal Cognition, 2021Co-Authors: Daria Valente, Jonah Ratsimbazafy, Valeria Torti, Chiara De Gregorio, Longondraza Miaretsoa, Olivier Friard, Anna Zanoli, Livio Favaro, Teresa Raimondi, Cristina GiacomaAbstract:Vocal and gestural sequences of several primates have been found to conform to two general principles of information compression: the compensation between the duration of a construct and that of its components (Menzerath–Altmann law) and an inverse relationship between signal duration and its occurrence (Zipf’s law of abbreviation). Even though Zipf’s law of brevity has been proposed as a universal in animal communication, evidence on non-human primate vocal behavior conformity to linguistic laws is still debated, and information on strepsirrhine primates is lacking. We analyzed the vocal behavior of the unique singing lemur species ( Indri Indri ) to assess whether the song of the species shows evidence for compression. As roars have a chaotic structure that impedes the recognition of each individual utterance, and long notes are usually given by males, we focused on the core part of the song (i.e., the descending phrases , composed of two–six units). Our results indicate that Indris’ songs conform to Zipf’s and Menzerath–Altmann linguistic laws. Indeed, shorter phrases are more likely to be included in the song, and units’ duration decrease at the increase of the size of the phrases. We also found that, despite a sexual dimorphism in the duration of both units and phrases, these laws characterize sequences of both males and females. Overall, we provide the first evidence for a trade-off between signal duration and occurrence in the vocal behavior of a strepsirrhine species, suggesting that selective pressures for vocal compression are more ancestral than previously assumed within primates.
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sexually dimorphic phrase organization in the song of the Indris Indri Indri
American Journal of Primatology, 2020Co-Authors: Anna Zanoli, Cristina Giacoma, Valeria Torti, Giovanna Bonadonna, Rose Marie Randrianarison, Daria Valente, Chiara De Gregorio, Marco GambaAbstract:Animal acoustic communication often takes the form of complex sequences, composed of multiple distinct acoustic units, which can vary in their degree of stereotypy. Studies of sequence variation may contribute to our understanding of the structural flexibility of primates' songs, which can provide essential ecological and behavioral information about variability at the individual, population, and specific level and provide insights into the mechanisms and drivers responsible for the evolutionary change of communicative traits. Several methods have been used for investigating different levels of structural information and sequence similarity in acoustic displays. We studied intra and interindividual variation in the song structuring of a singing primate, the Indri (Indri Indri), which inhabits the montane rain forests of Madagascar. Indri groups emit duets and choruses in which they combine long notes, short single units, and phrases consisting of a variable number of units (from two to six) with slightly descending frequency. Males' and females' contributions to the song differ in the temporal and frequency structure of song units and repertoire size. We calculated the similarity of phrase organization across different individual contributions using the Levenshtein distance, a logic distance that expressed the minimum cost to convert a sequence into another and can measure differences between two sequences of data. We then analyzed the degree of similarity within and between individuals and found that: (a) the phrase structure of songs varied between reproductive males and females: female structuring of the song showed a higher number of phrases if compared to males; (b) male contributions to the song were overall more similar to those of other males than were female contributions to the song of other females; (c) male contributions were more stereotyped than female contributions, which showed greater individual flexibility. The picture emerging from phrase combinatorics in the Indris is in agreement with previous findings of rhythmic features and song repertoire size of the Indris, which also suggested that female songs are potentially less stereotyped than those of males.
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Intra- and Intergroup Spatial Dynamics of a Pair-Living Singing Primate, Indri Indri: A Multiannual Study of Three Indri Groups in Maromizaha Forest, Madagascar
International Journal of Primatology, 2020Co-Authors: Giovanna Bonadonna, Marco Gamba, Valeria Torti, Rose Marie Randrianarison, Michele Zaccagno, Daria Valente, Chiara De Gregorio, Chia Tan, Cristina GiacomaAbstract:Territorial pair-living species tend to occupy and defend stable areas, assumed to contain all the resources needed for the lifetime of the group. Furthermore, groups have to mediate spatial relationships with neighboring groups. We investigated the relationship between social and spatial dynamics at the intra- and intergroup level in a pair-living territorial singing primate: the Indri ( Indri Indri ). We collected spatial data on three neighboring groups during 396 sampling days between 2009 and 2014 in Maromizaha forest, Madagascar. We evaluated the stability of territories in terms of size and location using minimum convex polygons, defined the presence and stability of core areas, and investigated if singing locations and intergroup encounters were concentrated in the core areas. Territories were generally stable in location and size, although some degree of territorial shift occurred, leading to readjustment of intergroup spacing. Groups had core areas that were not stable across years but were concentrated in the area of the territories that groups occupy consistently over time (stable areas). Singing locations were equally distributed inside and outside core areas, suggesting an even distribution through the territories; meanwhile 9 of 12 intergroup encounters took place in the core areas at the edge of territories. Together, our results support the pattern of territorial stability predicted for a pair-living species, where groups regulate territory exclusivity and spacing with neighbors. Singing behavior also plays an important role in mediating intergroup spatial dynamics. The spatial pattern we found in Indris is comparable with that found in other territorial and pair-living primates with different ecological needs, suggesting that in addition to ecological factors, social dynamics influence intergroup spatial dynamics.
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evidence of genetic monogamy in the lemur Indri Indri Indri
American Journal of Primatology, 2019Co-Authors: Giovanna Bonadonna, Marco Gamba, Valeria Torti, Rose Marie Randrianarison, Daria Valente, Chiara De Gregorio, Luca Pozzi, Cristina GiacomaAbstract:Monogamy is a rare strategy among mammals but relatively common among primates. The study of the evolution of monogamy in mammals and primates is lacking empirical studies that assess the relationship between a pair-living social organization and genetic monogamy. Sexual or genetic monogamy can only be assessed by performing molecular analyses and investigating rates of extra-pair paternity (EPP). Studying the occurrence of EPP can provide valuable insights into reproductive strategies and their adaptive value. The Indri is a pair-living primate that lives in stable groups. Their social units are composed of the reproductive pair and up to four more individuals, but extra-pair copulation (EPC) can occur. This raises the question of whether this event may or may not lead to EPP. Here, we investigated whether a pair-living social organization corresponds to genetic monogamy in Indris (Indri Indri). We analyzed the paternity of 12 offspring from seven pairs using a set of six microsatellite loci on fecal samples (mean number of alleles 11.7 ± 1.8 (mean ± standard deviation). We found that in 92% of cases the genetic profile of the offspring matched the paired male of the group for all the loci considered. In the only case of paternity mismatch, the paternity assignment remained inconclusive. Our results show that I. Indri genetic monogamy is the norm and supports the hypothesis that pair-living social organization is associated with low EPP rate. Also, our results are in contrast with the hypothesis of infertility as a reason to engage in EPC for this species.
Valeria Torti - One of the best experts on this subject based on the ideXlab platform.
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sex and age specific survival and life expectancy in a free ranging population of Indri Indri gmelin 1788
The European Zoological Journal, 2021Co-Authors: F Rolle, Cristina Giacoma, Valeria Torti, Daria Valente, C De Gregorio, A Von HardenbergAbstract:The critically endangered Indri (Indri Indri) is the largest extant lemur species and its population size is projected to decline over the next three generations due to habitat loss, hunting and cl...
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Linguistic laws of brevity: conformity in Indri Indri
Animal Cognition, 2021Co-Authors: Daria Valente, Jonah Ratsimbazafy, Valeria Torti, Chiara De Gregorio, Longondraza Miaretsoa, Olivier Friard, Anna Zanoli, Livio Favaro, Teresa Raimondi, Cristina GiacomaAbstract:Vocal and gestural sequences of several primates have been found to conform to two general principles of information compression: the compensation between the duration of a construct and that of its components (Menzerath–Altmann law) and an inverse relationship between signal duration and its occurrence (Zipf’s law of abbreviation). Even though Zipf’s law of brevity has been proposed as a universal in animal communication, evidence on non-human primate vocal behavior conformity to linguistic laws is still debated, and information on strepsirrhine primates is lacking. We analyzed the vocal behavior of the unique singing lemur species ( Indri Indri ) to assess whether the song of the species shows evidence for compression. As roars have a chaotic structure that impedes the recognition of each individual utterance, and long notes are usually given by males, we focused on the core part of the song (i.e., the descending phrases , composed of two–six units). Our results indicate that Indris’ songs conform to Zipf’s and Menzerath–Altmann linguistic laws. Indeed, shorter phrases are more likely to be included in the song, and units’ duration decrease at the increase of the size of the phrases. We also found that, despite a sexual dimorphism in the duration of both units and phrases, these laws characterize sequences of both males and females. Overall, we provide the first evidence for a trade-off between signal duration and occurrence in the vocal behavior of a strepsirrhine species, suggesting that selective pressures for vocal compression are more ancestral than previously assumed within primates.
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I Like the Way You Eat It: Lemur (Indri Indri) Gut Mycobiome and Geophagy
Microbial Ecology, 2021Co-Authors: Luigimaria Borruso, Caterina Spiezio, Alice Checcucci, Valeria Torti, Federico Correa, Camillo Sandri, Daine Luise, Luciano Cavani, Monica Modesto, Tanja MimmoAbstract:Here, we investigated the possible linkages among geophagy, soil characteristics, and gut mycobiome of Indri ( Indri Indri ), an endangered lemur species able to survive only in wild conditions. The soil eaten by Indri resulted in enriched secondary oxide-hydroxides and clays, together with a high concentration of specific essential micronutrients. This could partially explain the role of the soil in detoxification and as a nutrient supply. Besides, we found that soil subject to geophagy and Indris’ faeces shared about 8.9% of the fungal OTUs. Also, several genera (e.g. Fusarium , Aspergillus and Penicillium ) commonly associated with soil and plant material were found in both geophagic soil and Indri samples. On the contrary, some taxa with pathogenic potentials, such as Cryptococcus, were only found in Indri samples. Further, many saprotrophs and plant-associated fungal taxa were detected in the Indri faeces. These fungal species may be involved in the digestion processes of leaves and could have a beneficial role in their health. In conclusion, we found an intimate connection between gut mycobiome and soil, highlighting, once again, the potential consequent impacts on the wider habitat.
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I Like the Way You Eat It: the possible environmental drivers of Lemur (Indri Indri) Gut Microbiome and Mycobiome
2021Co-Authors: Federico Correa, Caterina Spiezio, Luigimaria Borruso, Alice Checcucci, Valeria Torti, Luciano Cavani, Monica Modesto, Tanja Mimmo, Stefano Cesco, Diana LuiseAbstract:Research on gut microbiome may help with increasing our understanding of primate health with species\u2019 ecology, evolution, and behavior. Microbiome-related information has the potential to clarify ecology issues, providing knowledge in support of wild primates\u2019 conservation and their associated habitats. Indri (Indri Indri) is the largest extant living lemur of Madagascar able to survive only in wild conditions. This species is classified as \u201ccritically endangered\u201d by the IUCN Red List of Threatened Species, representing one of the world\u2019s 25 most endangered primates. Indris diet is mainly folivorous, but these primates frequently and voluntarily engage in geophagy. Here, we investigated the possible linkages among geophagy, soil characteristics, and gut microbiome and mycobiome of Indri (Indri Indri). In these works, we explored the chemical composition of soil eaten by Indri, which resulted rich in secondary oxide-hydroxides and clays, together with a high concentration of specific essential micronutrients. This could partially explain the role of the soil in detoxification and as a nutrient supply. Then, we explored the gut microbiome composition of 18 Indris belonging to 5 different family groups. The most represented phyla were Proteobacteria 40.1 \ub1 9.5%, Bacteroidetes 28.7 \ub1 2.8%, and Synergistetes 16.7 \ub1 4.5%. Besides, we found that soil subject to geophagy and Indris\u2019 faeces shared about 8.9% of the fungal OTUs. Also, several genera (e.g. Fusarium, Aspergillus and Penicillium) were found in both geophagic soil and Indri samples. In conclusion, the intimate connection between gut mycobiome and soil, demonstrated that fungal species may be involved in the digestion processes of leaves and could have a beneficial role in their health. Altogether, the data presented in our works, provide a baseline for outlining some possible drivers responsible for the gut microbiome and mycobiome diversity in Indris, thus laying the foundations for developing further strategies involved in Indris\u2019 conservation
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disentangling the possible drivers of Indri Indri microbiome a threatened lemur species of madagascar
Frontiers in Microbiology, 2021Co-Authors: Federico Correa, Caterina Spiezio, Luigimaria Borruso, Alice Checcucci, Valeria Torti, Luciano Cavani, Tanja Mimmo, Stefano Cesco, Monica Marianna Modesto, Diana LuiseAbstract:Research on the gut microbiome may help with increasing our understanding of primate health with species' ecology, evolution, and behavior. In particular, microbiome-related information has the potential to clarify ecology issues, providing knowledge in support of wild primates conservation and their associated habitats. Indri (Indri Indri) is the largest extant living lemur of Madagascar. This species is classified as "critically endangered" by the IUCN Red List of Threatened Species, representing one of the world's 25 most endangered primates. Indris diet is mainly folivorous, but these primates frequently and voluntarily engage in geophagy. Indris have never been successfully bred under human care, suggesting that some behavioral and/or ecological factors are still not considered from the ex situ conservation protocols. Here, we explored gut microbiome composition of 18 Indris belonging to 5 different family groups. The most represented phyla were Proteobacteria 40.1 ± 9.5%, Bacteroidetes 28.7 ± 2.8%, Synergistetes 16.7 ± 4.5%, and Firmicutes 11.1 ± 1.9%. Further, our results revealed that bacterial alpha and beta diversity were influenced by Indri family group and sex. In addition, we investigated the chemical composition of geophagic soil to explore the possible ecological value of soil as a nutrient supply. The quite acidic pH and high levels of secondary oxide-hydroxides of the soils could play a role in the folivorous diet's gut detoxification activity. In addition, the high contents of iron and manganese found the soils could act as micronutrients in the Indris' diet. Nevertheless, the concentration of a few elements (i.e., calcium, sulfur, boron, nickel, sodium, and chromium) was higher in non-geophagic than in geophagic soils. In conclusion, the data presented herein provide a baseline for outlining some possible drivers responsible for the gut microbiome diversity in Indris, thus laying the foundations for developing further strategies involved in Indris' conservation.
Marco Gamba - One of the best experts on this subject based on the ideXlab platform.
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sexually dimorphic phrase organization in the song of the Indris Indri Indri
American Journal of Primatology, 2020Co-Authors: Anna Zanoli, Cristina Giacoma, Valeria Torti, Giovanna Bonadonna, Rose Marie Randrianarison, Daria Valente, Chiara De Gregorio, Marco GambaAbstract:Animal acoustic communication often takes the form of complex sequences, composed of multiple distinct acoustic units, which can vary in their degree of stereotypy. Studies of sequence variation may contribute to our understanding of the structural flexibility of primates' songs, which can provide essential ecological and behavioral information about variability at the individual, population, and specific level and provide insights into the mechanisms and drivers responsible for the evolutionary change of communicative traits. Several methods have been used for investigating different levels of structural information and sequence similarity in acoustic displays. We studied intra and interindividual variation in the song structuring of a singing primate, the Indri (Indri Indri), which inhabits the montane rain forests of Madagascar. Indri groups emit duets and choruses in which they combine long notes, short single units, and phrases consisting of a variable number of units (from two to six) with slightly descending frequency. Males' and females' contributions to the song differ in the temporal and frequency structure of song units and repertoire size. We calculated the similarity of phrase organization across different individual contributions using the Levenshtein distance, a logic distance that expressed the minimum cost to convert a sequence into another and can measure differences between two sequences of data. We then analyzed the degree of similarity within and between individuals and found that: (a) the phrase structure of songs varied between reproductive males and females: female structuring of the song showed a higher number of phrases if compared to males; (b) male contributions to the song were overall more similar to those of other males than were female contributions to the song of other females; (c) male contributions were more stereotyped than female contributions, which showed greater individual flexibility. The picture emerging from phrase combinatorics in the Indris is in agreement with previous findings of rhythmic features and song repertoire size of the Indris, which also suggested that female songs are potentially less stereotyped than those of males.
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Intra- and Intergroup Spatial Dynamics of a Pair-Living Singing Primate, Indri Indri: A Multiannual Study of Three Indri Groups in Maromizaha Forest, Madagascar
International Journal of Primatology, 2020Co-Authors: Giovanna Bonadonna, Marco Gamba, Valeria Torti, Rose Marie Randrianarison, Michele Zaccagno, Daria Valente, Chiara De Gregorio, Chia Tan, Cristina GiacomaAbstract:Territorial pair-living species tend to occupy and defend stable areas, assumed to contain all the resources needed for the lifetime of the group. Furthermore, groups have to mediate spatial relationships with neighboring groups. We investigated the relationship between social and spatial dynamics at the intra- and intergroup level in a pair-living territorial singing primate: the Indri ( Indri Indri ). We collected spatial data on three neighboring groups during 396 sampling days between 2009 and 2014 in Maromizaha forest, Madagascar. We evaluated the stability of territories in terms of size and location using minimum convex polygons, defined the presence and stability of core areas, and investigated if singing locations and intergroup encounters were concentrated in the core areas. Territories were generally stable in location and size, although some degree of territorial shift occurred, leading to readjustment of intergroup spacing. Groups had core areas that were not stable across years but were concentrated in the area of the territories that groups occupy consistently over time (stable areas). Singing locations were equally distributed inside and outside core areas, suggesting an even distribution through the territories; meanwhile 9 of 12 intergroup encounters took place in the core areas at the edge of territories. Together, our results support the pattern of territorial stability predicted for a pair-living species, where groups regulate territory exclusivity and spacing with neighbors. Singing behavior also plays an important role in mediating intergroup spatial dynamics. The spatial pattern we found in Indris is comparable with that found in other territorial and pair-living primates with different ecological needs, suggesting that in addition to ecological factors, social dynamics influence intergroup spatial dynamics.
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evidence of genetic monogamy in the lemur Indri Indri Indri
American Journal of Primatology, 2019Co-Authors: Giovanna Bonadonna, Marco Gamba, Valeria Torti, Rose Marie Randrianarison, Daria Valente, Chiara De Gregorio, Luca Pozzi, Cristina GiacomaAbstract:Monogamy is a rare strategy among mammals but relatively common among primates. The study of the evolution of monogamy in mammals and primates is lacking empirical studies that assess the relationship between a pair-living social organization and genetic monogamy. Sexual or genetic monogamy can only be assessed by performing molecular analyses and investigating rates of extra-pair paternity (EPP). Studying the occurrence of EPP can provide valuable insights into reproductive strategies and their adaptive value. The Indri is a pair-living primate that lives in stable groups. Their social units are composed of the reproductive pair and up to four more individuals, but extra-pair copulation (EPC) can occur. This raises the question of whether this event may or may not lead to EPP. Here, we investigated whether a pair-living social organization corresponds to genetic monogamy in Indris (Indri Indri). We analyzed the paternity of 12 offspring from seven pairs using a set of six microsatellite loci on fecal samples (mean number of alleles 11.7 ± 1.8 (mean ± standard deviation). We found that in 92% of cases the genetic profile of the offspring matched the paired male of the group for all the loci considered. In the only case of paternity mismatch, the paternity assignment remained inconclusive. Our results show that I. Indri genetic monogamy is the norm and supports the hypothesis that pair-living social organization is associated with low EPP rate. Also, our results are in contrast with the hypothesis of infertility as a reason to engage in EPC for this species.
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finding meanings in low dimensional structures stochastic neighbor embedding applied to the analysis of Indri Indri vocal repertoire
Open Access Journal, 2019Co-Authors: Daria Valente, Cristina Giacoma, Valeria Torti, Rose Marie Randrianarison, Chiara De Gregorio, Longondraza Miaretsoa, Olivier Friard, Marco GambaAbstract:Although there is a growing number of researches focusing on acoustic communication, the lack of shared analytic approaches leads to inconsistency among studies. Here, we introduced a computational method used to examine 3360 calls recorded from wild Indris (Indri Indri) from 2005–2018. We split each sound into ten portions of equal length and, from each portion we extracted spectral coefficients, considering frequency values up to 15,000 Hz. We submitted the set of acoustic features first to a t-distributed stochastic neighbor embedding algorithm, then to a hard-clustering procedure using a k-means algorithm. The t-distributed stochastic neighbor embedding (t-SNE) mapping indicated the presence of eight different groups, consistent with the acoustic structure of the a priori identification of calls, while the cluster analysis revealed that an overlay between distinct call types might exist. Our results indicated that the t-distributed stochastic neighbor embedding (t-SNE), successfully been employed in several studies, showed a good performance also in the analysis of Indris’ repertoire and may open new perspectives towards the achievement of shared methodical techniques for the comparison of animal vocal repertoires.
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call and be counted can we reliably estimate the number of callers in the Indri s Indri Indri song
PLOS ONE, 2018Co-Authors: Valeria Torti, Cristina Giacoma, Jonah Ratsimbazafy, Daria Valente, Chiara De Gregorio, Longondraza Miaretsoa, Carlo Comazzi, Marco GambaAbstract:Estimating the number of animals participating in a choral display may contribute reliable information on animal population estimates, particularly when environmental or behavioral factors restrict the possibility of visual surveys. Difficulties in providing a reliable estimate of the number of singers in a chorus are many (e.g., background noise masking, overlap). In this work, we contributed data on the vocal chorusing of the Indri lemurs (Indri Indri), which emit howling cries, known as songs, uttered by two to five individuals. We examined whether we could estimate the number of emitters in a chorus by screening the fundamental frequency in the spectrograms and the total duration of the songs, and the reliability of those methods when compared to the real chorus size. The spectrographic investigation appears to provide reliable information on the number of animals participating in the chorusing only when this number is limited to two or three singers. We also found that the Acoustic Complexity Index positively correlated with the real chorus size, showing that an automated analysis of the chorus may provide information about the number of singers. We can state that song duration shows a correlation with the number of emitters but also shows a remarkable variation that remains unexplained. The accuracy of the estimates can reflect the high variability in chorus size, which could be affected by group composition, season and context. In future research, a greater focus on analyzing frequency change occurring during these collective vocal displays should improve our ability to detect individuals and allow a finer tuning of the acoustic methods that may serve for monitoring chorusing mammals.
Matthias F Bickelhaupt - One of the best experts on this subject based on the ideXlab platform.
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indenyl effect due to metal slippage computational exploration of rhodium catalyzed acetylene 2 2 2 cyclotrimerization
ChemPhysChem, 2014Co-Authors: Laura Orian, Marcel Swart, Matthias F BickelhauptAbstract:The mechanism of CpRh (Cp=cyclopentadienyl) and IndRh (Ind=indenyl)-catalyzed acetylene [2+2+2] cyclotrimerization has been revisited aiming at finding an explanation for the better performance of the latter catalyst found experimentally. The hypothesis that an ancillary ligand of the precatalyst remains bonded to the metal center throughout the whole catalytic cycle, based on the experimental evidence that the nature of this ligand can exert some control in cocyclotrimerization of different alkynes, is considered. Strong hapticity variations occur in both the CpRh- and IndRh-catalyzed processes. As the Ind ligand undergoes a more facile slippage than Cp, the energy profile is far smoother in the IndRh-catalyzed cyclotrimerization. This difference in the energetics of the process translates into an enhanced activity of the IndRh catalyst, in nice agreement with experiment.
Daria Valente - One of the best experts on this subject based on the ideXlab platform.
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sex and age specific survival and life expectancy in a free ranging population of Indri Indri gmelin 1788
The European Zoological Journal, 2021Co-Authors: F Rolle, Cristina Giacoma, Valeria Torti, Daria Valente, C De Gregorio, A Von HardenbergAbstract:The critically endangered Indri (Indri Indri) is the largest extant lemur species and its population size is projected to decline over the next three generations due to habitat loss, hunting and cl...
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Linguistic laws of brevity: conformity in Indri Indri
Animal Cognition, 2021Co-Authors: Daria Valente, Jonah Ratsimbazafy, Valeria Torti, Chiara De Gregorio, Longondraza Miaretsoa, Olivier Friard, Anna Zanoli, Livio Favaro, Teresa Raimondi, Cristina GiacomaAbstract:Vocal and gestural sequences of several primates have been found to conform to two general principles of information compression: the compensation between the duration of a construct and that of its components (Menzerath–Altmann law) and an inverse relationship between signal duration and its occurrence (Zipf’s law of abbreviation). Even though Zipf’s law of brevity has been proposed as a universal in animal communication, evidence on non-human primate vocal behavior conformity to linguistic laws is still debated, and information on strepsirrhine primates is lacking. We analyzed the vocal behavior of the unique singing lemur species ( Indri Indri ) to assess whether the song of the species shows evidence for compression. As roars have a chaotic structure that impedes the recognition of each individual utterance, and long notes are usually given by males, we focused on the core part of the song (i.e., the descending phrases , composed of two–six units). Our results indicate that Indris’ songs conform to Zipf’s and Menzerath–Altmann linguistic laws. Indeed, shorter phrases are more likely to be included in the song, and units’ duration decrease at the increase of the size of the phrases. We also found that, despite a sexual dimorphism in the duration of both units and phrases, these laws characterize sequences of both males and females. Overall, we provide the first evidence for a trade-off between signal duration and occurrence in the vocal behavior of a strepsirrhine species, suggesting that selective pressures for vocal compression are more ancestral than previously assumed within primates.
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sexually dimorphic phrase organization in the song of the Indris Indri Indri
American Journal of Primatology, 2020Co-Authors: Anna Zanoli, Cristina Giacoma, Valeria Torti, Giovanna Bonadonna, Rose Marie Randrianarison, Daria Valente, Chiara De Gregorio, Marco GambaAbstract:Animal acoustic communication often takes the form of complex sequences, composed of multiple distinct acoustic units, which can vary in their degree of stereotypy. Studies of sequence variation may contribute to our understanding of the structural flexibility of primates' songs, which can provide essential ecological and behavioral information about variability at the individual, population, and specific level and provide insights into the mechanisms and drivers responsible for the evolutionary change of communicative traits. Several methods have been used for investigating different levels of structural information and sequence similarity in acoustic displays. We studied intra and interindividual variation in the song structuring of a singing primate, the Indri (Indri Indri), which inhabits the montane rain forests of Madagascar. Indri groups emit duets and choruses in which they combine long notes, short single units, and phrases consisting of a variable number of units (from two to six) with slightly descending frequency. Males' and females' contributions to the song differ in the temporal and frequency structure of song units and repertoire size. We calculated the similarity of phrase organization across different individual contributions using the Levenshtein distance, a logic distance that expressed the minimum cost to convert a sequence into another and can measure differences between two sequences of data. We then analyzed the degree of similarity within and between individuals and found that: (a) the phrase structure of songs varied between reproductive males and females: female structuring of the song showed a higher number of phrases if compared to males; (b) male contributions to the song were overall more similar to those of other males than were female contributions to the song of other females; (c) male contributions were more stereotyped than female contributions, which showed greater individual flexibility. The picture emerging from phrase combinatorics in the Indris is in agreement with previous findings of rhythmic features and song repertoire size of the Indris, which also suggested that female songs are potentially less stereotyped than those of males.
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Intra- and Intergroup Spatial Dynamics of a Pair-Living Singing Primate, Indri Indri: A Multiannual Study of Three Indri Groups in Maromizaha Forest, Madagascar
International Journal of Primatology, 2020Co-Authors: Giovanna Bonadonna, Marco Gamba, Valeria Torti, Rose Marie Randrianarison, Michele Zaccagno, Daria Valente, Chiara De Gregorio, Chia Tan, Cristina GiacomaAbstract:Territorial pair-living species tend to occupy and defend stable areas, assumed to contain all the resources needed for the lifetime of the group. Furthermore, groups have to mediate spatial relationships with neighboring groups. We investigated the relationship between social and spatial dynamics at the intra- and intergroup level in a pair-living territorial singing primate: the Indri ( Indri Indri ). We collected spatial data on three neighboring groups during 396 sampling days between 2009 and 2014 in Maromizaha forest, Madagascar. We evaluated the stability of territories in terms of size and location using minimum convex polygons, defined the presence and stability of core areas, and investigated if singing locations and intergroup encounters were concentrated in the core areas. Territories were generally stable in location and size, although some degree of territorial shift occurred, leading to readjustment of intergroup spacing. Groups had core areas that were not stable across years but were concentrated in the area of the territories that groups occupy consistently over time (stable areas). Singing locations were equally distributed inside and outside core areas, suggesting an even distribution through the territories; meanwhile 9 of 12 intergroup encounters took place in the core areas at the edge of territories. Together, our results support the pattern of territorial stability predicted for a pair-living species, where groups regulate territory exclusivity and spacing with neighbors. Singing behavior also plays an important role in mediating intergroup spatial dynamics. The spatial pattern we found in Indris is comparable with that found in other territorial and pair-living primates with different ecological needs, suggesting that in addition to ecological factors, social dynamics influence intergroup spatial dynamics.
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evidence of genetic monogamy in the lemur Indri Indri Indri
American Journal of Primatology, 2019Co-Authors: Giovanna Bonadonna, Marco Gamba, Valeria Torti, Rose Marie Randrianarison, Daria Valente, Chiara De Gregorio, Luca Pozzi, Cristina GiacomaAbstract:Monogamy is a rare strategy among mammals but relatively common among primates. The study of the evolution of monogamy in mammals and primates is lacking empirical studies that assess the relationship between a pair-living social organization and genetic monogamy. Sexual or genetic monogamy can only be assessed by performing molecular analyses and investigating rates of extra-pair paternity (EPP). Studying the occurrence of EPP can provide valuable insights into reproductive strategies and their adaptive value. The Indri is a pair-living primate that lives in stable groups. Their social units are composed of the reproductive pair and up to four more individuals, but extra-pair copulation (EPC) can occur. This raises the question of whether this event may or may not lead to EPP. Here, we investigated whether a pair-living social organization corresponds to genetic monogamy in Indris (Indri Indri). We analyzed the paternity of 12 offspring from seven pairs using a set of six microsatellite loci on fecal samples (mean number of alleles 11.7 ± 1.8 (mean ± standard deviation). We found that in 92% of cases the genetic profile of the offspring matched the paired male of the group for all the loci considered. In the only case of paternity mismatch, the paternity assignment remained inconclusive. Our results show that I. Indri genetic monogamy is the norm and supports the hypothesis that pair-living social organization is associated with low EPP rate. Also, our results are in contrast with the hypothesis of infertility as a reason to engage in EPC for this species.
