3,235 research outputs found
Hedging our bets: the expected contribution of species to future phylogenetic diversity
If predictions for species extinctions hold, then the `tree of life' today
may be quite different to that in (say) 100 years. We describe a technique to
quantify how much each species is likely to contribute to future biodiversity,
as measured by its expected contribution to phylogenetic diversity. Our
approach considers all possible scenarios for the set of species that will be
extant at some future time, and weights them according to their likelihood
under an independent (but not identical) distribution on species extinctions.
Although the number of extinction scenarios can typically be very large, we
show that there is a simple algorithm that will quickly compute this index. The
method is implemented and applied to the prosimian primates as a test case, and
the associated species ranking is compared to a related measure (the `Shapley
index'). We describe indices for rooted and unrooted trees, and a modification
that also includes the focal taxon's probability of extinction, making it
directly comparable to some new conservation metrics.Comment: 19 pages, 2 figure
Trait and phylogenetic diversity provide insights into community assembly of reefāassociated shrimps (Palaemonidae) at different spatial scales across the Chagos Archipelago
Coral reefs are the most biodiverse marine ecosystem and one of the most threatened by global climate change impacts. The vast majority of diversity on reefs is comprised of small invertebrates that live within the reef structure, termed the cryptofauna. This component of biodiversity is hugely understudied, and many species remain undescribed. This study represents a rare analysis of assembly processes structuring a distinct group of cryptofauna, the Palaemonidae, in the Chagos Archipelago, a reef ecosystem under minimal direct human impacts in the central Indian Ocean. The Palaemonidae are a diverse group of Caridae (infraorder of shrimps) that inhabit many different niches on coral reefs and are of particular interest because of their varied habitat associations. Phylogenetic and trait diversity and phylogenetic signal were used to infer likely drivers of community structure. The mechanisms driving palaemonid community assembly and maintenance in the Chagos Archipelago showed distinct spatial patterns. At local scales, among coral colonies and among reefs fringing individual atolls, significant trait, and phylogenetic clustering patterns suggest environmental filtering may be a dominant ecological process driving Palaemonidae community structure, although local competition through equalizing mechanisms may also play a role in shaping the local community structure. Importantly, we also tested the robustness of phylogenetic diversity to changes in evolutionary information as multiāgene phylogenies are resource intensive and for large families, such as the Palaemonidae, are often incomplete. These tests demonstrated a very modest impact on phylogenetic community structure, with only one of the four genes (PEPCK gene) in the phylogeny affecting phylogenetic diversity patterns, which provides useful information for future studies on large families with incomplete phylogenies. These findings contribute to our limited knowledge of this component of biodiversity in a marine locality as close to undisturbed by humans as can be found. It also provides a rare evaluation of phylogenetic diversity methods
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