Taxonomic evolution in North American Neogene horses (subfamily Equinae): the rise and fall of an adaptive radiation

Paleobiology ◽  
1993 ◽  
Vol 19 (2) ◽  
pp. 216-234 ◽  
Author(s):  
Richard C. Hulbert
Keyword(s):  
Species Richness ◽  
Steady State ◽  
Adaptive Radiation ◽  
Middle Miocene ◽  
Extinction Rate ◽  
Extinction Rates ◽  
Speciation Rates ◽  
History Of ◽  
Very High ◽  
Radiation Phase

The 18 m.y. history of the subfamily Equinae (exclusive of Archaeohippus and “Parahippus”) in North America consisted of a 3-m.y. radiation phase, a 9-m.y. steady-state diversity phase, and a 6-m.y. reduction phase. During the steady-state phase, species richness varied between 14 and 20, with two maxima at about 13.5 and 6.5 Ma. Species richness of the tribes Hipparionini and Equini was about equal through the middle Miocene, but hipparionines consistently had more species in the late Miocene and early Pliocene. Overall mean species duration was 3.2 m.y. (n = 50), or an average extinction rate of 0.31 m.y.-1 During the radiation phase, speciation rates were very high (0.5 to 1.4 m.y.-1), while extinction rates were low (<0.10 m.y.-1). Speciation and extinction rates both averaged about 0.15 m.y.-1 during the steady-state phase, with extinction rates having more variation. Extinction rates increased fourfold during the reduction phase, while speciation rates declined slightly. Late Hemphillian extinctions affected both tribes severely, not just the three-toed hipparionines, and were correlated with global climatic change.

scholarly journals Graptoloid evolutionary rates track Ordovician–Silurian global climate change

2013 ◽  
Vol 151 (2) ◽  
pp. 349-364 ◽  
Author(s):  
ROGER A. COOPER ◽  
PETER M. SADLER ◽  
AXEL MUNNECKE ◽  
JAMES S. CRAMPTON
Keyword(s):  
Species Richness ◽  
Evolutionary Dynamics ◽  
Global Climate ◽  
Mean Value ◽  
Evolutionary Rates ◽  
Extinction Rate ◽  
Extinction Rates ◽  
History Of ◽  
Mass Depletion ◽  
Climatic Regime

AbstractGraptoloid evolutionary dynamics show a marked contrast from the Ordovician to the Silurian. Subdued extinction and origination rates during the Ordovician give way, during the late Katian, to rates that were highly volatile and of higher mean value through the Silurian, reflecting the significantly shorter lifespan of Silurian species. These patterns are revealed in high-resolution rate curves derived from the CONOP (constrained optimization) scaled and calibrated global composite sequence of 2094 graptoloid species. The end-Ordovician mass depletion was driven primarily by an elevated extinction rate which lasted forc. 1.2 Ma with two main spikes during the Hirnantian. The early Silurian recovery, although initiated by a peak in origination rate, was maintained by a complex interplay of origination and extinction rates, with both rates rising and falling sharply. The global δ13C curve echoes the graptoloid evolutionary rates pattern; the prominent and well-known positive isotope excursions during the Late Ordovician and Silurian lie on or close to times of sharp decline in graptoloid species richness, commonly associated with extinction rate spikes. The graptoloid and isotope data point to a relatively steady marine environment in the Ordovician with mainly background extinction rates, changing during the Katian to a more volatile climatic regime that prevailed through the Silurian, with several sharp extinction episodes triggered by environmental crises. The correlation of graptoloid species diversity with isotopic ratios was positive in the Ordovician and negative in the Silurian, suggesting different causal linkages. Throughout the history of the graptoloid clade all major depletions in species richness except for one were caused by elevated extinction rate rather than decreased origination rate.

scholarly journals Reconciliation ecology and the future of species diversity

Oryx ◽  
2003 ◽  
Vol 37 (2) ◽  
pp. 194-205 ◽  
Author(s):  
Michael L. Rosenzweig
Keyword(s):  
Steady State ◽  
Species Diversity ◽  
Natural Area ◽  
Reconciliation Ecology ◽  
Anthropogenic Habitats ◽  
Extinction Rates ◽  
Broad Array ◽  
Speciation Rates ◽  
Species Area ◽  
Biogeographical Province

Species-area relationships (SPARs) dictate a sea change in the strategies of biodiversity conservation. SPARs exist at three ecological scales: Sample-area SPARs (a larger area within a biogeographical province will tend to include more habitat types, and thus more species, than a smaller one), Archipelagic SPARs (the islands of an archipelago show SPARs that combine the habitat-sampling process with the problem of dispersal to an island), and Interprovincial SPARs (other things being equal, the speciation rates of larger biogeographical provinces are higher and their extinction rates are lower, leading to diversities in proportion to provincial area). SPARs are the products of steady-state dynamics in diversity, and such dynamics appears to have characterized the earth for most of the last 500 million years. As people reduce the area available to wild species, they impose a linear reduction of the earth's species diversity that will follow the largest of these scales, i.e. each 1% reduction of natural area will cost about 1% of steady-state diversity. Reserving small tracts of wild habitat can only delay these reductions. But we can stop most of them by redesigning anthropogenic habitats so that their use is compatible with use by a broad array of other species. That is reconciliation ecology. Many pilot projects, whether intentionally or inadvertently espousing reconciliation ecology, are demonstrating that it can be done.

scholarly journals Phylogenetic diversity as a window into the evolutionary and biogeographic histories of present-day richness gradients for mammals

2011 ◽  
Vol 366 (1576) ◽  
pp. 2414-2425 ◽  
Author(s):  
T. Jonathan Davies ◽  
Lauren B. Buckley
Keyword(s):  
Species Richness ◽  
Phylogenetic Diversity ◽  
Diversity Indices ◽  
Environmental Predictors ◽  
Terrestrial Mammals ◽  
Extinction Rates ◽  
Biogeographic History ◽  
Shared Ancestry ◽  
History Of ◽  
Dispersal Events

Phylogenetic diversity (PD) captures the shared ancestry of species, and is increasingly being recognized as a valuable conservation currency. Regionally, PD frequently covaries closely with species richness; however, variation in speciation and extinction rates and/or the biogeographic history of lineages can result in significant deviation. Locally, these differences may be pronounced. Rapid recent speciation or high temporal turnover of lineages can result in low PD but high richness. In contrast, rare dispersal events, for example, between biomes, can elevate PD but have only small impact on richness. To date, environmental predictors of species richness have been well studied but global models explaining variation in PD are lacking. Here, we contrast the global distribution of PD versus species richness for terrestrial mammals. We show that an environmental model of lineage diversification can predict well the discrepancy in the distribution of these two variables in some places, for example, South America and Africa but not others, such as Southeast Asia. When we have information on multiple diversity indices, conservation efforts directed towards maximizing one currency or another (e.g. species richness versus PD) should also consider the underlying processes that have shaped their distributions.

scholarly journals Analysis of temporal diversification of African Cyprinidae (Teleostei, Cypriniformes)

ZooKeys ◽  
2018 ◽  
Vol 806 ◽  
pp. 141-161 ◽  
Author(s):  
Mariam I. Adeoba ◽  
Kowiyou Yessoufou
Keyword(s):  
Bayes Factor ◽  
Extinction Rate ◽  
Fish Family ◽  
Evolutionary Diversification ◽  
History Of ◽  
Rapid Diversification ◽  
Freshwater System ◽  
African Cichlids ◽  
Wide Geographic Distribution ◽  
Very High

Recent evidence that freshwater fishes diversify faster than marine fishes signifies that the evolutionary history of biodiversity in freshwater system is of particular interest. Here, the evolutionary diversification events of African Cyprinidae, a freshwater fish family with wide geographic distribution, were reconstructed and analysed. The overall diversification rate of African Cyprinidae is 0.08 species per million year (when extinction rate is very high, i.e., ε = 0.9) and 0.11 species per million year (when ε = 0). This overall rate is lower than the rate reported for African Cichlids, suggesting that African freshwaters might be less conducive for a rapid diversification of Cyprinidae. However, the observed diversification events of African Cyprinidae occurred in the last 10 million years. The temporal pattern of these events follows a non-constant episodic birth-death model (Bayes Factor &gt; 28) and the rate-constant model never outperformed any of the non-constant models tested. The fact that most diversification events occurred in the last 10 million years supports the pattern reported for Cyprinidae in other continent, e.g., Asia, perhaps pointing to concomitant diversification globally. However, the diversification events coincided with major geologic and paleo-climatic events in Africa, suggesting that geological and climatic events may have mediated the diversification patterns of Cyprinidae on the continent.

scholarly journals Earth history events shaped the evolution of uneven biodiversity across tropical moist forests

2021 ◽  
Vol 118 (40) ◽  
pp. e2026347118 ◽  
Author(s):  
Oskar Hagen ◽  
Alexander Skeels ◽  
Renske E. Onstein ◽  
Walter Jetz ◽  
Loïc Pellissier
Keyword(s):  
Species Richness ◽  
Terrestrial Plants ◽  
Spatially Explicit Model ◽  
Deep Time ◽  
Extinction Rates ◽  
Speciation Rates ◽  
Tectonic Reconstructions ◽  
The Relationship ◽  
Contemporary Climate

Far from a uniform band, the biodiversity found across Earth’s tropical moist forests varies widely between the high diversity of the Neotropics and Indomalaya and the relatively lower diversity of the Afrotropics. Explanations for this variation across different regions, the “pantropical diversity disparity” (PDD), remain contentious, due to difficulty teasing apart the effects of contemporary climate and paleoenvironmental history. Here, we assess the ubiquity of the PDD in over 150,000 species of terrestrial plants and vertebrates and investigate the relationship between the present-day climate and patterns of species richness. We then investigate the consequences of paleoenvironmental dynamics on the emergence of biodiversity gradients using a spatially explicit model of diversification coupled with paleoenvironmental and plate tectonic reconstructions. Contemporary climate is insufficient in explaining the PDD; instead, a simple model of diversification and temperature niche evolution coupled with paleoaridity constraints is successful in reproducing the variation in species richness and phylogenetic diversity seen repeatedly among plant and animal taxa, suggesting a prevalent role of paleoenvironmental dynamics in combination with niche conservatism. The model indicates that high biodiversity in Neotropical and Indomalayan moist forests is driven by complex macroevolutionary dynamics associated with mountain uplift. In contrast, lower diversity in Afrotropical forests is associated with lower speciation rates and higher extinction rates driven by sustained aridification over the Cenozoic. Our analyses provide a mechanistic understanding of the emergence of uneven diversity in tropical moist forests across 110 Ma of Earth’s history, highlighting the importance of deep-time paleoenvironmental legacies in determining biodiversity patterns.

scholarly journals On the processes generating latitudinal richness gradients: identifying diagnostic patterns and predictions

2014 ◽  
Author(s):  
Allen H Hurlbert ◽  
James C Stegen
Keyword(s):  
Species Richness ◽  
Negative Relationship ◽  
Niche Conservatism ◽  
Glacial Cycles ◽  
Climatic Fluctuations ◽  
Extinction Rates ◽  
Available Energy ◽  
Speciation Rates ◽  
Tropical Climates ◽  
The Tropics

Many processes have been put forward to explain the latitudinal gradient in species richness. Here, we use a simulation model to examine four of the most common hypotheses and identify patterns that might be diagnostic of those four hypotheses. The hypotheses examined include (1) tropical niche conservatism, or the idea that the tropics are more diverse because a tropical clade origin has allowed more time for diversification in the tropics and has resulted in few species adapted to extra-tropical climates. (2) The productivity, or energetic constraints, hypothesis suggests that species richness is limited by the amount of biologically available energy in a region. (3) The tropical stability hypothesis argues that major climatic fluctuations and glacial cycles in extratropical regions have led to greater extinction rates and less opportunity for specialization relative to the tropics. (4) Finally, the speciation rates hypothesis suggests that the latitudinal richness gradient arises from a parallel gradient in rates of speciation. We found that tropical niche conservatism can be distinguished from the other three scenarios by phylogenies which are more balanced than expected, no relationship between mean root distance and richness across regions, and a homogeneous rate of speciation across clades and through time. The energy gradient, speciation gradient, and disturbance gradient scenarios all exhibited phylogenies which were more imbalanced than expected, showed a negative relationship between mean root distance and richness, and diversity-dependence of speciation rate estimates through time. Using Bayesian Analysis of Macroevolutionary Mixtures on the simulated phylogenies, we found that the relationship between speciation rates and latitude could distinguish among these three scenarios. We emphasize the importance of considering multiple hypotheses and focusing on diagnostic predictions instead of predictions that are consistent with more than one hypothesis.

A kinetic model of Phanerozoic taxonomic diversity II. Early Phanerozoic families and multiple equilibria

Paleobiology ◽  
1979 ◽  
Vol 5 (3) ◽  
pp. 222-251 ◽  
Author(s):  
J. John Sepkoski
Keyword(s):  
Kinetic Model ◽  
Multiple Equilibria ◽  
Dynamic Equilibrium ◽  
Taxonomic Diversity ◽  
Extinction Rate ◽  
Two Phase ◽  
Extinction Rates ◽  
History Of ◽  
Extinction Events ◽  
Middle And Late Cambrian

The kinetic model of taxonomic diversity predicts that the long-term diversification of taxa within any large and essentially closed ecological system should approximate a logistic process controlled by changes in origination and extinction rates with changing numbers of taxa. This model is tested with a new compilation of numbers of metazoan families known from Paleozoic stages (including stage-level subdivisions of the Cambrian). These data indicate the occurrence of two intervals of logistic diversification within the Paleozoic. The first interval, spanning the Vendian and Cambrian, includes an approximately exponential increase in families across the Precambrian-Cambrian Boundary and a “pseudo-equilibrium” through the Middle and Late Cambrian, caused by diversity-dependent decrease in origination rate and increase in extinction rate. The second interval begins with a rapid re-diversification in the Ordovician, which leads to a tripling of familial diversity during a span of 50 Myr; by the end of the Ordovician diversity attains a new dynamic equilibrium that is maintained, except for several extinction events, for nearly 200 Myr until near the end of the Paleozoic. A “two-phase” kinetic model is constructed to describe this heterogeneous pattern of early Phanerozoic diversification. The model adequately describes the “multiple equilibria,” the asymmetrical history of the “Cambrian fauna,” the extremely slow initial diversification of the later “Paleozoic fauna,” and the combined patterns of origination and extinction in both faunas. It is suggested that this entire pattern of diversification reflects the early success of ecologically generalized taxa and their later replacement by more specialized taxa.

scholarly journals Fast diversification through a mosaic of evolutionary histories characterizes the endemic flora of ancient Neotropical mountains

2020 ◽  
Vol 287 (1923) ◽  
pp. 20192933 ◽  
Author(s):  
Thais N. C. Vasconcelos ◽  
Suzana Alcantara ◽  
Caroline O. Andrino ◽  
Félix Forest ◽  
Marcelo Reginato ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Species Turnover ◽  
Plant Species Richness ◽  
Campo Rupestre ◽  
Population Isolation ◽  
Mountain Ranges ◽  
Extinction Rates ◽  
Speciation Rates ◽  
Endemic Flora

Mountains are among the most biodiverse areas on the globe. In young mountain ranges, exceptional plant species richness is often associated with recent and rapid radiations linked to the mountain uplift itself. In ancient mountains, however, orogeny vastly precedes the evolution of vascular plants, so species richness has been explained by species accumulation during long periods of low extinction rates. Here we evaluate these assumptions by analysing plant diversification dynamics in the campo rupestre , an ecosystem associated with pre-Cambrian mountaintops and highlands of eastern South America, areas where plant species richness and endemism are among the highest in the world. Analyses of 15 angiosperm clades show that radiations of endemics exhibit fastest rates of diversification during the last 5 Myr, a climatically unstable period. However, results from ancestral range estimations using different models disagree on the age of the earliest in situ speciation events and point to a complex floristic assembly. There is a general trend for higher diversification rates associated with these areas, but endemism may also increase or reduce extinction rates, depending on the group. Montane habitats, regardless of their geological age, may lead to boosts in speciation rates by accelerating population isolation in archipelago-like systems, circumstances that can also result in higher extinction rates and fast species turnover, misleading the age estimates of endemic lineages.

scholarly journals Settling down of seasonal migrants promotes bird diversification

2014 ◽  
Vol 281 (1784) ◽  
pp. 20140473 ◽  
Author(s):  
Jonathan Rolland ◽  
Frédéric Jiguet ◽  
Knud Andreas Jønsson ◽  
Fabien L. Condamine ◽  
Hélène Morlon
Keyword(s):  
Species Richness ◽  
Sedentary Behaviour ◽  
Evolutionary History ◽  
Seasonal Migration ◽  
Migratory Behaviour ◽  
Migratory Species ◽  
Diversification Rates ◽  
Extinction Rates ◽  
History Of ◽  
Daughter Species

How seasonal migration originated and impacted diversification in birds remains largely unknown. Although migratory behaviour is likely to affect bird diversification, previous studies have not detected any effect. Here, we infer ancestral migratory behaviour and the effect of seasonal migration on speciation and extinction dynamics using a complete bird tree of life. Our analyses infer that sedentary behaviour is ancestral, and that migratory behaviour evolved independently multiple times during the evolutionary history of birds. Speciation of a sedentary species into two sedentary daughter species is more frequent than speciation of a migratory species into two migratory daughter species. However, migratory species often diversify by generating a sedentary daughter species in addition to the ancestral migratory one. This leads to an overall higher migratory speciation rate. Migratory species also experience lower extinction rates. Hence, although migratory species represent a minority (18.5%) of all extant birds, they have a higher net diversification rate than sedentary species. These results suggest that the evolution of seasonal migration in birds has facilitated diversification through the divergence of migratory subpopulations that become sedentary, and illustrate asymmetrical diversification as a mechanism by which diversification rates are decoupled from species richness.

scholarly journals Dissecting the paleocontinental and paleoenvironmental dynamics of the great Ordovician biodiversification

Paleobiology ◽  
2019 ◽  
Vol 45 (02) ◽  
pp. 221-234 ◽  
Author(s):  
Franziska Franeck ◽  
Lee Hsiang Liow
Keyword(s):  
High Energy ◽  
Extinction Rate ◽  
Time Intervals ◽  
Diversification Rates ◽  
Extinction Rates ◽  
Regional Dynamics ◽  
Genus Richness ◽  
Very High

AbstractThe Ordovician was a time of drastic biological and geological change. Previous work has suggested that there was a dramatic increase in global diversity during this time, but also has indicated that regional dynamics and dynamics in specific environments might have been different. Here, we contrast two paleocontinents that have different geological histories through the Ordovician, namely Laurentia and Baltica. The first was situated close to the equator throughout the whole Ordovician, while the latter has traversed tens of latitudes during the same time. We predict that Baltica, which was under long-term environmental change, would show greater average and interval-to-interval origination and extinction rates than Laurentia. In addition, we are interested in the role of the environment in which taxa originated, specifically, the patterns of onshore–offshore dynamics of diversification, where onshore and offshore areas represent high-energy and low-energy environments, respectively. Here, we predict that high-energy environments might be more conducive for originations.Our new analyses show that the global Ordovician spike in genus richness from the Dapingian to the Darriwilian Stage resulted from a very high origination rate at the Dapingian/Darriwilian boundary, while the extinction rate remained low. We found substantial interval-to-interval variation in the origination and extinction rates in Baltica and Laurentia, but the probabilities of origination and extinction are somewhat higher in Baltica than Laurentia. Onshore and offshore areas have largely indistinguishable origination and extinction rates, in contradiction to our predictions. The global spike in origination rates at the Dapingian/Darriwilian boundary is apparent in Baltica, Laurentia, and onshore and offshore areas, and abundant variability in diversification rates is apparent over other time intervals for these paleocontinents and paleoenvironments. This observation hints at global mechanisms for the spike in origination rates at the Dapingian/Darriwilian boundary but a domination of more regional and local mechanisms over other time intervals in the Ordovician.

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