Progress to extinction: increased specialisation causes the demise of animal clades

Raia, Pasquale; Carotenuto, Francesco; Mondanaro, Alessandro; Castiglione, Silvia; Passaro, Federico; Saggese, Fiorella; Melchionna, Marina; Serio, Carmela; Alessio, L.; Silvestro, Daniele; Fortelius, Mikael

doi:10.1038/srep30965

Cited by 38 publications

(43 citation statements)

References 51 publications

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“…], or pollinator loss [Steiner and Whitehead ]) or natural (e.g., as documented by the fossil record over 480 million years; Raia et al. ). Defining ecological specialisation can be controversial (Devictor et al.…”

Section: Discussionmentioning

confidence: 99%

Evaluating alternative explanations for an association of extinction risk and evolutionary uniqueness in multiple insular lineages

et al. 2018

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Studies in insular environments have often documented a positive association of extinction risk and evolutionary uniqueness (i.e., how distant a species is from its closest living relative). However, the cause of this association is unclear. One explanation is that species threatened with extinction are evolutionarily unique because they are old, implying that extinction risk increases with time since speciation (age-dependent extinction). An alternative explanation is that such threatened species are last survivors of clades that have undergone an elevated extinction rate, and that their uniqueness results from the extinction of their close relatives. Distinguishing between these explanations is difficult but important, since they imply different biological processes determining extinction patterns. Here, we designed a simulation approach to distinguish between these alternatives using living species, and applied it to 12 insular radiations that show a positive association between extinction risk and evolutionary uniqueness. We also tested the sensitivity of results to underlying assumptions and variable extinction rates. Despite differences among the radiations considered, age-dependent extinction was supported as best explaining the majority of the empirical cases. Biological processes driving characteristic changes in abundance with species duration (age-dependency) may merit further investigation.

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Section: Discussionmentioning

confidence: 99%

Evaluating alternative explanations for an association of extinction risk and evolutionary uniqueness in multiple insular lineages

et al. 2018

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“…Slowdown in the rate of lineage accumulation over time has been observed in fossil records [4, 40–42] as well as molecular phylogenies of clades of animals [1,2,4] and plants [43]. Such slowdown could be due to ecological density-dependence, but also to other causes such as adaptive radiation [2,44], protracted speciation [45], incorrect or incomplete phylogenies [41,46,47], niche filling, or other causes [5].…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the term density- or diversity- dependence should not be used indiscriminately when diversification slows down, but only when there is evidence of causal density-dependence. Ideally, to distinguish density-dependence from alternative explanations, future analyses of diversification slowdown should take species geographic distribution [42], 2016) and phenotypic differences [22,48] into account [5], and not rely solely on the global numbers of species in a clade.…”

Section: Discussionmentioning

confidence: 99%

Does density-dependent diversification mirror ecological competitive exclusion?

Monroe

Bokma

2017

PLoS ONE

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Density-dependence is a term used in ecology to describe processes such as birth and death rates that are regulated by the number of individuals in a population. Evolutionary biologists have borrowed the term to describe decreasing rates of species accumulation, suggesting that speciation and extinction rates depend on the total number of species in a clade. If this analogy with ecological density-dependence holds, diversification of clades is restricted because species compete for limited resources. We hypothesize that such competition should not only affect numbers of species, but also prevent species from being phenotypically similar. Here, we present a method to detect whether competitive interactions between species have ordered phenotypic traits on a phylogeny, assuming that competition prevents related species from having identical trait values. We use the method to analyze clades of birds and mammals, with body size as the phenotypic trait. We find no sign that competition has prevented species from having the same body size. Thus, since body size is a key ecological trait and competition does not seem to be responsible for differences in body size between species, we conclude that the diversification slowdown that is prevalent in these clades is unlikely due to the ecological interference implied by the term density dependence.

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“…Two palaeontological studies are consistent with this alternative perspective: Liow () found that species with longer fossil durations have average trait values, while Raia et al . () found that specialization led to increased extinction of entire clades. If it is reasonable to assume that ‘average morphologies’ are groups of species that would contribute little to total TR, and specialization results in groups of species that contribute more to TR, these findings suggest a negative correlation between TR and per capita extinction rate.…”

Section: Evaluating the Arguments For Evolutionary Historymentioning

confidence: 99%

Assessing the utility of conserving evolutionary history

et al. 2019

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It is often claimed that conserving evolutionary history is more efficient than species‐based approaches for capturing the attributes of biodiversity that benefit people. This claim underpins academic analyses and recommendations about the distribution and prioritization of species and areas for conservation, but evolutionary history is rarely considered in practical conservation activities. One impediment to implementation is that arguments related to the human‐centric benefits of evolutionary history are often vague and the underlying mechanisms poorly explored. Herein we identify the arguments linking the prioritization of evolutionary history with benefits to people, and for each we explicate the purported mechanism, and evaluate its theoretical and empirical support. We find that, even after 25 years of academic research, the strength of evidence linking evolutionary history to human benefits is still fragile. Most – but not all – arguments rely on the assumption that evolutionary history is a useful surrogate for phenotypic diversity. This surrogacy relationship in turn underlies additional arguments, particularly that, by capturing more phenotypic diversity, evolutionary history will preserve greater ecosystem functioning, capture more of the natural variety that humans prefer, and allow the maintenance of future benefits to humans. A surrogate relationship between evolutionary history and phenotypic diversity appears reasonable given theoretical and empirical results, but the strength of this relationship varies greatly. To the extent that evolutionary history captures unmeasured phenotypic diversity, maximizing the representation of evolutionary history should capture variation in species characteristics that are otherwise unknown, supporting some of the existing arguments. However, there is great variation in the strength and availability of evidence for benefits associated with protecting phenotypic diversity. There are many studies finding positive biodiversity–ecosystem functioning relationships, but little work exists on the maintenance of future benefits or the degree to which humans prefer sets of species with high phenotypic diversity or evolutionary history. Although several arguments link the protection of evolutionary history directly with the reduction of extinction rates, and with the production of relatively greater future biodiversity via increased adaptation or diversification, there are few direct tests. Several of these putative benefits have mismatches between the relevant spatial scales for conservation actions and the spatial scales at which benefits to humans are realized. It will be important for future work to fill in some of these gaps through direct tests of the arguments we define here.

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Progress to extinction: increased specialisation causes the demise of animal clades

Cited by 38 publications

References 51 publications

Evaluating alternative explanations for an association of extinction risk and evolutionary uniqueness in multiple insular lineages

Evaluating alternative explanations for an association of extinction risk and evolutionary uniqueness in multiple insular lineages

Does density-dependent diversification mirror ecological competitive exclusion?

Assessing the utility of conserving evolutionary history

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