Reproductive Strategy

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Nicolas Châline - One of the best experts on this subject based on the ideXlab platform.

  • drifting behaviour as an alternative Reproductive Strategy for social insect workers
    Proceedings of The Royal Society B: Biological Sciences, 2013
    Co-Authors: Pierre Blacher, Boris Yagound, Emmanuel Lecoutey, Paul Devienne, Stephane Chameron, Nicolas Châline

    Restricted reproduction is traditionally posited as the defining feature of eusocial insect workers. The discovery of worker reproduction in foreign colonies challenges this view and suggests that workers’ potential to pursue selfish interests may be higher than previously believed. However, whether such Reproductive behaviour truly relies on a Reproductive decision is still unknown. Workers’ Reproductive decisions thus need to be investigated to assess the extent of workers’ Reproductive options. Here, we show in the bumblebee Bombus terrestris that drifting is a distinct Strategy by which fertile workers circumvent competition in their nest and reproduce in foreign colonies. By monitoring workers’ movements between colonies, we show that drifting is a remarkably dynamic behaviour, widely expressed by both fertile and infertile workers. We demonstrate that a high fertility is, however, central in determining the propensity of workers to enter foreign colonies as well as their subsequent reproduction in host colonies. Moreover, our study shows that the drifting of fertile workers reflects complex decision-making processes associated with in-nest Reproductive competition. This novel finding therefore adds to our modern conception of cooperation by showing the previously overlooked importance of alternative strategies which enable workers to assert their Reproductive interests.

Pierre Freon - One of the best experts on this subject based on the ideXlab platform.

  • small pelagic fish Reproductive strategies in upwelling systems a natal homing evolutionary model to study environmental constraints
    Progress in Oceanography, 2009
    Co-Authors: Timothee Brochier, Luis A Cubillos, Francois Colas, Christophe Lett, Vincent Echevin, M Chlaida, Christian Mullon, Pierre Freon

    Although little is known about the individual-level mechanisms that influence small pelagic fish species’ Reproductive Strategy, Mullon et al. [Mullon, C., Cury, P., Penven, P., 2002. Evolutionary individual-based model for the recruitment of anchovy (Engraulis capensis) in the southern Benguela. Canadian Journal of Fisheries and Aquatic Sciences 59, 910–922] showed that the observed anchovy spawning patterns in the southern Benguela Current system off South Africa could be accurately reproduced by simulating a natal homing Reproductive Strategy, i.e. individuals spawning at their natal date and place. Here we used a similar method, i.e., an individual-based model of the natal homing Reproductive Strategy, and applied it to other upwelling systems: the northern Humboldt Current system off Peru, the southern Humboldt Current system off Chile and the central Canary Current system off Morocco. We investigated the spatial (horizontal and vertical) and seasonal spawning patterns that emerged after applying different environmental constraints in the model, and compared these to observed spawning patterns of sardine and anchovy in their respective systems. The selective environmental constraints tested were: (1) lethal temperature; (2) retention over the continental shelf; and (3) avoidance of dispersive structures. Simulated horizontal spatial patterns and seasonal patterns compared reasonably well with field data, but vertical patterns in most cases did not. Similarly to what was found for the southern Benguela, temperature was a determinant constraint in the southern Humboldt. The shelf retention constraint led to selection of a particular spawning season during the period of minimum upwelling in all three of the upwelling regions considered, and to spatial patterns that matched observed anchovy spawning off Chile and sardine spawning off Morocco. The third constraint, avoidance of dispersive structures, led to the emergence of a spawning season during the period of maximum upwelling off Chile and Morocco, but not in Peru. The most accurate representation of observed spatio-temporal spawning patterns off Peru was achieved through a combination of shelf retention and non-dispersion constraints.

Patrizia Jereb - One of the best experts on this subject based on the ideXlab platform.

  • male Reproductive system and spermatophores production and storage in histioteuthis bonnellii cephalopoda histioteuthidae a look into deep sea squids Reproductive Strategy
    Deep Sea Research Part I: Oceanographic Research Papers, 2014
    Co-Authors: Danila Cuccu, Marco Mereu, Angelo Cau, Blondine Agus, Jacopo Culurgioni, Andrea Sabatini, Patrizia Jereb

    Abstract Coleoid cephalopods go through a single breeding period in their life cycle, i.e., they are semelparous, although a great flexibility has been observed in their Reproductive strategies, which range from simultaneous terminal spawning over a short period at the end of the animal׳s life to continuous spawning over a long period of the animal׳s life. So far, the information available on deep-sea species Reproductive strategies is still poor and most of our knowledge about squid reproduction relates to females. In particular, not much is known on what Strategy male squids have evolved to store sperm into spermatophores and adapt to semelparity. In this study an investigation of male Reproductive Strategy of the deep-sea umbrella squid Histioteuthis bonnellii (Ferussac, 1835) is presented. The Reproductive system was examined in 119 males caught in the Sardinian waters (Central Western Mediterranean) and is described for the first time. Results indicate that this species produces and stores spermatophores over a considerable period of time. The total number of spermatophores found in the Reproductive system ranged between 12 and 3097 and the size of spermatophores stored by a single individual varied greatly, up to over 300%. Spermatophore length (SpL) gradually decreased towards the distal end of the Reproductive system, so that spermatophores found in the proximal part of Needham׳s Sac were larger than those found in the terminal organ. Body size and SpL of spermatophores from the proximal part of Needham׳s Sac were positively correlated. Both indices of the sperm mass and of the ejaculatory apparatus decreased with the increase of SpL, while the cement body index increased, indicating that larger spermatophores contain less sperm and are equipped with larger cement bodies. Up to 64 spermatangia were found, exclusively in the terminal organ. The large size range of mature males (ML: 60.0–198.0 mm; TW: 113.50–2409.00 g) and the variation in spermatophore number and size indicate that in H. bonnellii males the allocation and storage of sperm start early in the individual life and extends in time, while animals continue to grow and produce spermatophores presumably more successful in attaching to female tissues. This pattern enlarges the time window available for reproduction and likely maximizes the percentage of mating success as the animals grow older and chances of mating events become comparatively lower, due to the basic low density of specimens in the deep-sea environment. Both aspects are potentially indicative of adaptation to the deep sea.

Lammertjan Dam - One of the best experts on this subject based on the ideXlab platform.

  • the male Reproductive Strategy of a deep sea squid sperm allocation continuous production and long term storage of spermatophores in histioteuthis miranda
    Ices Journal of Marine Science, 2010
    Co-Authors: Hendrik Jan T Hoving, Marek R Lipinski, Lammertjan Dam

    Squid are semelparous organisms. Much of what we know about squid reproduction relates to females, because few studies have addressed males and, although males are similarly challenged by semelparity, it remains virtually unknown what tactics squid have evolved to allocate sperm to spermatophores. The male Reproductive Strategy of the deep-sea squid Histioteuthis miranda was examined by describing the male Reproductive anatomy, which appears unique among cephalopods, and by quantifying spermatophore production and sperm allocation. The species produces and stores spermatophores over a considerable period of continuous somatic growth. Body size and spermatophore length (SpL) are positively correlated, and the size difference between spermatophores stored by a single individual was up to 270%. Individuals had between 136 and 2276 spermatophores inside their Reproductive system, and spermatophores may be stored for as long as 4.5 months. The relationship between SpL and the mass of sperm per spermatophore was polynomial, demonstrating that larger spermatophores did not necessarily contain more sperm. The unique male morphology and the continuous production and long-term storage of spermatophores in H. miranda seem to allow the species to increase the window in which reproduction can take place, a Strategy that may be valuable in the deep-sea environment.

Marilyn B. Renfree - One of the best experts on this subject based on the ideXlab platform.

  • Unique Reproductive Strategy in the swamp wallaby.
    Proceedings of the National Academy of Sciences of the United States of America, 2020
    Co-Authors: Brandon R. Menzies, Thomas B. Hildebrandt, Marilyn B. Renfree

    Reproduction in mammals requires distinct cycles of ovulation, fertilization, pregnancy, and lactation often interspersed with periods of anoestrus when breeding does not occur. Macropodids, the largest extant species of marsupials, the kangaroos and wallabies, have a very different Reproductive Strategy to most eutherian mammals whereby young are born at a highly altricial stage of development with the majority of development occurring over a lengthy lactation period. Furthermore, the timings of ovulation and birth in some species occurs within a very short interval of each other (sometimes hours). Female swamp wallabies have an oestrous cycle shorter than their pregnancy length and were, therefore, speculated to mate and form a new embryo before birth thereby supporting two conceptuses at different stages of pregnancy. To confirm this, we used high-resolution ultrasound to monitor reproduction in swamp wallabies during pregnancy. Here, we show that females ovulate, mate, and form a new embryo prepartum while still carrying a full-term fetus in the contralateral uterus. This embryo enters embryonic diapause until the newborn leaves the pouch 9 mo later. Thus, combined with embryonic diapause, females are continuously pregnant and lactating at the same time throughout their Reproductive life, a unique Reproductive Strategy that completely blurs the normal staged system of reproduction in mammals.