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Gil-santana, Hélcio R. - One of the best experts on this subject based on the ideXlab platform.

Alves, Ruy José Válka - One of the best experts on this subject based on the ideXlab platform.

Válka Alves, Ruy José - One of the best experts on this subject based on the ideXlab platform.

Matthew L. Knope - One of the best experts on this subject based on the ideXlab platform.

  • Invasive congeners are unlikely to hybridize with native Hawaiian Bidens (Asteraceae)
    American journal of botany, 2013
    Co-Authors: Matthew L. Knope, Richard J. Pender, Daniel J. Crawford, Ania M. Wieczorek
    Abstract:

     Premise of the study: Invasive plant species threaten native plants in multiple ways, one of which is genetic assimilation through hybridization. However, information regarding hybridization between related alien and native plant species is generally lacking. In Hawaii, the invasive Central American species Bidens pilosa and Bidens alba have colonized natural areas and often grow alongside the native Hawaiian Bidens species, a clade representing an adaptive radiation of 27 endemic taxa, many of which are threatened or endangered.  Methods: To assess the risk of hybridization between introduced and native Hawaiian Bidens (which will readily hybridize with one another), we undertook crosses in cultivation between the invasive species and nine native Bidens taxa.  Key results: The majority of the crosses formed no viable seed. Although seed did mature in several of the crosses, morphological screening of the resulting seedlings indicated that they were the result of self-pollination.  Conclusions: This result suggests that B. alba and B. pilosa are incapable of hybridizing with these Hawaiian Bidens taxa. Further, we found that B. alba in Hawaii was self-compatible, despite self-incompatibility throughout its native range, and that the tetraploid species B. alba and the hexaploid species B. pilosa were cross-compatible, although pollen fertility was low.

  • area and the rapid radiation of hawaiian Bidens asteraceae
    Journal of Biogeography, 2012
    Co-Authors: Matthew L. Knope, Clifford W Morden, Vicki A Funk, Tadashi Fukami
    Abstract:

    Aim  To estimate the rate of adaptive radiation of endemic Hawaiian Bidens and to compare their diversification rates with those of other plants in Hawaii and elsewhere with rapid rates of radiation. Location  Hawaii. Methods  Fifty-nine samples representing all 19 Hawaiian species, six Hawaiian subspecies, two Hawaiian hybrids and an additional two Central American and two African Bidens species had their DNA extracted, amplified by polymerase chain reaction and sequenced for four chloroplast and two nuclear loci, resulting in a total of approximately 5400 base pairs per individual. Internal transcribed spacer sequences for additional outgroup taxa, including 13 non-Hawaiian Bidens, were obtained from GenBank. Phylogenetic relationships were assessed by maximum likelihood and Bayesian inference. The age of the most recent common ancestor and diversification rates of Hawaiian Bidens were estimated using the methods of previously published studies to allow for direct comparison with other studies. Calculations were made on a per-unit-area basis. Results  We estimate the age of the Hawaiian clade to be 1.3–3.1 million years old, with an estimated diversification rate of 0.3–2.3 species/million years and 4.8 × 10−5 to 1.3 × 10−4 species Myr−1 km−2. Bidens species are found in Europe, Africa, Asia and North and South America, but the Hawaiian species have greater diversity of growth form, floral morphology, dispersal mode and habitat type than observed in the rest of the genus world-wide. Despite this diversity, we found little genetic differentiation among the Hawaiian species. This is similar to the results from other molecular studies on Hawaiian plant taxa, including others with great morphological variability (e.g. silverswords, lobeliads and mints). Main conclusions  On a per-unit-area basis, Hawaiian Bidens have among the highest rates of speciation for plant radiations documented to date. The rapid diversification within such a small area was probably facilitated by the habitat diversity of the Hawaiian Islands and the adaptive loss of dispersal potential. Our findings point to the need to consider the spatial context of diversification – specifically, the relative scale of habitable area, environmental heterogeneity and dispersal ability – to understand the rate and extent of adaptive radiation.

  • ARTICLE Area and the rapid radiation of Hawaiian Bidens (Asteraceae)
    2012
    Co-Authors: Matthew L. Knope, Clifford W Morden, Vicki A Funk, Tadashi Fukami
    Abstract:

    Aim To estimate the rate of adaptive radiation of endemic Hawaiian Bidens and to compare their diversification rates with those of other plants in Hawaii and elsewhere with rapid rates of radiation. Location Hawaii. Methods Fifty-nine samples representing all 19 Hawaiian species, six Hawaiian subspecies, two Hawaiian hybrids and an additional two Central American and two African Bidens species had their DNA extracted, amplified by polymerase chain reaction and sequenced for four chloroplast and two nuclear loci, resulting in a total of approximately 5400 base pairs per individual. Internal transcribed spacer sequences for additional outgroup taxa, including 13 non-Hawaiian Bidens, were obtained from GenBank. Phylogenetic relationships were assessed by maximum likelihood and Bayesian inference. The age of the most recent common ancestor and diversification rates of Hawaiian Bidens were estimated using the methods of previously published studies to allow for direct comparison with other studies. Calculations were made on a per-unit-area basis. Results We estimate the age of the Hawaiian clade to be 1.3‐3.1 million years old, with an estimated diversification rate of 0.3‐2.3 species/million years and 4.8 · 10 )5 to 1.3 · 10 )4 species Myr )1 km )2 . Bidens species are found in Europe, Africa, Asia and North and South America, but the Hawaiian species have greater diversity of growth form, floral morphology, dispersal mode and habitat type than observed in the rest of the genus world-wide. Despite this diversity, we found little genetic differentiation among the Hawaiian species. This is similar to the results from other molecular studies on Hawaiian plant taxa, including others with great morphological variability (e.g. silverswords, lobeliads and mints). Main conclusions On a per-unit-area basis, Hawaiian Bidens have among the highest rates of speciation for plant radiations documented to date. The rapid diversification within such a small area was probably facilitated by the habitat diversity of the Hawaiian Islands and the adaptive loss of dispersal potential. Our findings point to the need to consider the spatial context of diversification ‐ specifically, the relative scale of habitable area, environmental heterogeneity and dispersal ability ‐ to understand the rate and extent of adaptive radiation.

Ruy José Válka Alves - One of the best experts on this subject based on the ideXlab platform.