Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids

Adaptive radiations are central to macroevolutionary theory. Whether triggered by acquisition of new traits or ecological opportunities arising from mass extinctions, it is debated whether adaptive radiations are marked by initial expansion of taxic diversity or of morphological disparity (the range of anatomical form). If a group rediversifies following a mass extinction, it is said to have passed through a macroevolutionary bottleneck, and the loss of taxic or phylogenetic diversity may limit the amount of morphological novelty that it can subsequently generate. Anomodont therapsids, a diverse clade of Permian and Triassic herbivorous tetrapods, passed through a bottleneck during the end-Permian mass extinction. Their taxic diversity increased during the Permian, declined significantly at the Permo–Triassic boundary and rebounded during the Middle Triassic before the clade''s final extinction at the end of the Triassic. By sharp contrast, disparity declined steadily during most of anomodont history. Our results highlight three main aspects of adaptive radiations: (i) diversity and disparity are generally decoupled; (ii) models of radiations following mass extinctions may differ from those triggered by other causes (e.g. trait acquisition); and (iii) the bottleneck caused by a mass extinction means that a clade can emerge lacking its original potential for generating morphological variety.     

An elevational shift in butterfly species richness and composition accompanying recent climate change

The geographic ranges of many species have shifted polewards and uphill in elevation associated with climate warming, leading to increases in species richness at high latitudes and elevations. However, few studies have addressed community‐level responses to climate change across the entire elevational gradients of mountain ranges, or at warm lower latitudes where ecological diversity is expected to decline. Here, we show uphill shifts in butterfly species richness and composition in the Sierra de Guadarrama (central Spain) between 1967–1973 and 2004–2005. Butterfly communities with comparable species compositions shifted uphill by 293 m (± SE 26), consistent with an upward shift of approximately 225 m in mean annual isotherms. Species richness had a humped relationship with elevation, but declined between surveys, particularly at low elevations. Changes to species richness and composition primarily reflect the loss from lower elevations of species whose regional distributions are restricted to the mountains. The few colonizations by specialist low‐elevation species failed to compensate for the loss of high‐elevation species, because there are few low‐elevation species in the region and the habitat requirements of some of these prevent them from colonizing the mountain range. As a result, we estimated a net decline in species richness in approximately 90% of the region, and increasing community domination by widespread species. The results suggest that climate warming, combined with habitat loss and other drivers of biological change, could lead to significant losses in ecological diversity in mountains and other regions where species encounter their lower latitudinal‐range margins.     

Taxon age,origination, and extinction through geologic time

Changes in the taxon ages of fossil marine families that are alive and those that become extinct in each stage of the Phanerozoic reflect changes in the origination rate, differences in the extinction rate of families with different taxon ages, and mass extinction events. Extinct families are generally much younger than the population from which they were drawn. Periods dominated by higher numbers of younger families are more susceptible to larger size extinctions and greater variation in extinction size. As a result the relative size of extinction peaks must be viewed with regard to the taxon age structure of the population. Mass extinctions cause little change in the taxon age of the fauna. However, adaptive radiations cause a large drop in the average age of the families that are alive at any given time. Families must be treated as dynamic entities in macroevolutionary studies because their probabilities of extinction change over time.     

The tropics: cradle,museum or casino? A dynamic null model for latitudinal gradients of species diversity

Several ecological and evolutionary hypotheses have been proposed to explain the latitudinal diversity gradient (LDG), but a general model for this conspicuous pattern remains elusive. Mid-domain effect (MDE) models generate gradients of species diversity by randomly placing the geographic ranges of species in one- or two-dimensional spaces, thus excluding both evolutionary processes and the effect of contemporary climate. Traditional MDE models are statistical and static because they determine the size of ranges either randomly or based on empirical frequency distributions. Here we present a simple dynamic null model for the LDG that simulates stochastic processes of range shifts, extinction and speciation. The model predicts higher species diversity and higher extinction and speciation rates in the tropics, and a strong influence of range movements in shaping the LDG. These null expectations should be taken into consideration in studies aimed at understanding the many factors that generate latitudinal diversity gradients.     

中国野生杜鹃花属植物名录与地理分布数据集

杜鹃花属(Rhododendron)植物分布广泛, 生存环境多样, 类群结构复杂, 深入分析其地理分布格局与特征, 可为种质资源保育和利用等提供依据。本文基于大量基础数据及文献资料, 更新了中国陆域分布的野生杜鹃花属植物物种名录, 统计了其物种多样性、组成成分等信息, 建立了中国野生杜鹃花属植物地理分布数据库, 旨在为种质资源调查及引种应用研究提供参考。截至2021年7月, 共记载7亚属720种(包括114变种、45亚种和2变型), 其中中国特有种450种。除宁夏和新疆干旱荒漠地带外, 中国其他各省区均有野生杜鹃花属分布, 其中云南省分布393种, 是省级尺度物种丰富度及特有性最高的区域; 其次为四川省(278种)及西藏自治区(271种)。县级尺度贡山独龙族怒族自治县与察隅县以134种并列物种丰富度第一, 其次是德钦县128种。     

Population and geographic range dynamics: implications for conservation planning

Continuing downward trends in the population sizes of many species, in the conservation status of threatened species, and in the quality, extent and connectedness of habitats are of increasing concern. Identifying the attributes of declining populations will help predict how biodiversity will be impacted and guide conservation actions. However, the drivers of biodiversity declines have changed over time and average trends in abundance or distributional change hide significant variation among species. While some populations are declining rapidly, the majority remain relatively stable and others are increasing. Here we dissect out some of the changing drivers of population and geographic range change, and identify biological and geographical correlates of winners and losers in two large datasets covering local population sizes of vertebrates since 1970 and the distributions of Galliform birds over the last two centuries. We find weak evidence for ecological and biological traits being predictors of local decline in range or abundance, but stronger evidence for the role of local anthropogenic threats and environmental change. An improved understanding of the dynamics of threat processes and how they may affect different species will help to guide better conservation planning in a continuously changing world.     

中国野生凤仙花属物种多样性和地理分布数据集

凤仙花属(Impatiens)植物主要分布于旧世界的热带和亚热带山区, 对生长环境要求极度严苛, 深入分析其地理分布格局与特征, 可为种质资源调查和利用提供理论依据。本研究通过系统检索文献资料, 更新了该属植物物种名录, 整合其地理分布、海拔、特有性等信息, 建立了中国野生凤仙花属植物地理分布数据库。截至2022年3月, 中国共记载野生凤仙花属植物352种(包含18变种1亚种1变型), 其中中国特有种273种。除上海市外, 中国其他各省级行政区均有野生凤仙花属植物分布, 其中云南省分布有165种, 其次为四川省(119种)和西藏自治区(69种)。县级尺度上, 贡山独龙族怒族自治县和腾冲市以51种并列物种丰富度第一, 其次是福贡县(42种)。中国野生凤仙花属的分布总体呈现以热带、亚热带为中心向高纬度和高海拔区域扩散的格局, 广义横断山区、西藏南部地区、滇黔桂喀斯特区域、长江中下游等地为凤仙花属植物集中分布的热点地区。     

Evolutionary age and risk of extinction in the global avifauna

Species at high risk of extinction are not distributed at random among higher taxa. Here we demonstrate that there is a positive relationship between the proportion of species in a taxon which are considered to be threatened and the evolutionary age of that taxon, both for the global avifauna and the avifauna of the New World. The potential mechanisms and consequences of the relationship are examined.