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58 results for “diversification dynamics”

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Data for manuscript: Extinction pulse at Eocene–Oligocene boundary drives diversification dynamics of the two Australian temperate floras

The diversification dynamics of the Australian temperate flora remains poorly understood. Here, we investigate whether differences in plant richness in the southwest Australian biodiversity hotspot (SWA) and southeast (SEA) regions of the Australian continent can be attributed to higher net diversification, more time for species accumulation, or both. We assembled dated molecular phylogenies for the 21 most species-rich flowering plant families found across mesic temperate Australia, encompassing both SWA and SEA regions, and applied a series of diversification models to investigate responses across different groups and time scales. We show that the high richness in SWA can be attributed to a higher net rate of lineage diversification and more time for species accumulation. Different pulses of diversification were retrieved in each region. A decrease in diversification rate across major flowering plant lineages at the Eocene–Oligocene boundary (c. 34 Ma) was witnessed in SEA but not in SW A.

opencc-zeroDec 2020View details →

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Taxon pulse dynamics, episodic dispersal, and host colonization across Beringia drive diversification of a holarctic tapeworm assemblage

Aim: We test the predictions of the Stockholm Paradigm, a synthesis of eco-evolutionary theory explaining the nature of faunal assembly, host range and parasite diversification. Faunal diversification and assembly, manifested in patterns of host colonization, co-adaptation and parasite speciation, is predicted to emerge as a consequence of alternating episodes of ecological disruption and stability. Specifically, for a diverse cestode genus (Arostrilepis), we evaluate the number and direction of Pleistocene dispersal events across Beringia, the number and relative timing of host colonization events, and the relationship between host and parasite biogeographic histories and associations through time. Location: Beringia and adjacent temperate to arctic biomes in North America and Eurasia. Taxon: Arostrilepis (Cyclophyllidea: Hymenolepididae) and its rodent hosts. Methods: Multi-locus phylogenetic reconstruction and biogeographic ancestral range estimation. Results: Arostrilepis lineages crossed Beringia eastward into North America a minimum of four times and westward into Asia twice in association with temporally disjunct geographic expansions of three major tribes of cricetid rodents (Arvicolini, Myodini, Lemmini). Inferences of ancestral host associations support at least nine instances of host-colonization involving shifts from one rodent tribe or family to another. Several previously unrecognized lineages of Arostrilepis are revealed. Main conclusions: Consistent with expectations of the Stockholm Paradigm, episodes of intercontinental dispersal were both frequent in the history of Arostrilepis and preceded a majority of inferred host-colonization events. Events of historical geographic expansion created numerous opportunities for development of novel host-parasite associations through ecological fitting, as parasites tracked historically conserved resources available across diverse host taxa. Beringia played a major role in shaping rodent/parasite assemblages by mediating dispersal between the northern continents during glacial episodes of the Pleistocene, rather than by serving as a zone of refugial isolation.

opencc-zeroAug 2021View details →

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Data from: Dissecting biodiversity in a global hotspot: uneven dynamics of immigration and diversification within the Cape Floristic Region of South Africa

Aim: Fragmented distributions should show immigration and diversification dynamics consistent with the predictions of island biogeography theory. We test whether this applies to the fragmented Cape fynbos vegetation. Location: Southern Africa, Cape Floristic Region (CFR) Taxon: Angiosperms, Restionaceae (restios) Methods: We used a large occurrence dataset and environmental layers to characterize an existing regionalization and the intervals between the regions ecologically and spatially. We extended the available phylogeny for restios and inferred their historical biogeography using models implemented in BioGeoBEARS. We then measured the relative contribution of immigration and in situ speciation to the species richness of each region within the CFR. We used standard statistical methods to test the predictions of the island biogeography theory. Results: The area and environmental heterogeneity of the seven regions of the CFR are positively correlated with in situ speciation rate. Furthermore, more isolated areas, and areas colonized more recently, have proportionally higher immigration rates, and more central and older areas proportionally higher in situ speciation rates. Main Conclusions: The variation in immigration and diversification dynamics among the regions within the CFR is extensive and consistent with the archipelago model of island biography theory. This dynamic may contribute significantly to the diversity of the Cape flora. Such a model could be generally useful for understanding the generation and maintenance of diversity in biodiversity hotspots, and may even scale up to explain continental biodiversity.

opencc-zeroJul 2019View details →

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Data from: Macroevolutionary dynamics in the early diversification of Asteraceae

Spatial and temporal differences in ecological opportunity can result in disparity of net species diversification rates and consequently uneven distribution of taxon richness across the tree of life. The largest eudicotyledonous plant family Asteraceae has a global distribution and at least 460 times more species than its South American endemic sister family Calyceraceae. In this study, diversification rate dynamics across Asteraceae are examined in light of the several hypothesized causes for the family's evolutionary success that could be responsible for rate change. The innovations of racemose capitulum and pappus, and a whole genome duplication event occurred near the origin of the family, yet we found the basal lineages of Asteraceae that evolved in South America share background diversification rates with Calyceraceae and their Australasian sister Goodeniaceae. Instead we found diversification rates increased gradually from the origin of Asteraceae approximately 69.5 Ma in the late Cretaceous through the Early Eocene Climatic Optimum at least. In contrast to earlier studies, significant rate shifts were not strongly correlated with intercontinental dispersals or polyploidization. The difference is due primarily to sampling more backbone nodes, as well as calibrations placed internally in Asteraceae that resulted in earlier divergence times than those found in most previous relaxed clock studies. Two clades identified as having transformed rate processes are the Vernonioid Clade and a clade within the Heliantheae alliance characterized by phytomelanic fruit (PF Clade) that represents an American radiation. In Africa, subfamilies Carduoideae, Pertyoideae, Gymnarrhenoideae, Cichorioideae, Corymbioideae, and Asteroideae diverged in a relatively short span of only 6.5 million years during the Middle Eocene.

opencc-zeroDec 2015View details →

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Data from: Mosaic patterns of diversification dynamics following the colonization of Melanesian islands

The fate of newly settled dispersers on freshly colonized oceanic islands is a central theme of island biogeography. The emergence of increasingly sophisticated methods of macroevolutionary pattern inference paves the way for a deeper understanding of the mechanisms governing these diversification patterns on lineages following their colonization of oceanic islands. Here we infer a comprehensive molecular phylogeny for Melanesian Exocelina diving beetles. Recent methods in historical biogeography and diversification rate inference were then used to investigate the evolution of these insects in space and time. An Australian origin in the mid-Miocene was followed by independent colonization events towards New Guinea and New Caledonia in the late Miocene. One colonization of New Guinea led to a large radiation of >150 species and 3 independent colonizations of New Caledonia gave rise to about 40 species. The comparably late colonizations of Vanuatu, Hawaii and China left only one or two species in each region. The contrasting diversification trajectories of these insects on Melanesian islands are likely accounted for by island size, age and availability of ecological opportunities during the colonization stage.

opencc-zeroDec 2014View details →

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Data from: Geographic and temporal dynamics of a global radiation and diversification in the killer whale

Global climate change during the Late Pleistocene periodically encroached and then released habitat during the glacial cycles, causing range expansions and contractions in some species. These dynamics have played a major role in geographic radiations, diversification and speciation. We investigate these dynamics in the most widely distributed of marine mammals, the killer whale (Orcinus orca), using a global data set of over 450 samples. This marine top predator inhabits coastal and pelagic ecosystems ranging from the ice edge to the tropics, often exhibiting ecological, behavioural and morphological variation suggestive of local adaptation accompanied by reproductive isolation. Results suggest a rapid global radiation occurred over the last 350 000 years. Based on habitat models, we estimated there was only a 15% global contraction of core suitable habitat during the last glacial maximum, and the resources appeared to sustain a constant global effective female population size throughout the Late Pleistocene. Reconstruction of the ancestral phylogeography highlighted the high mobility of this species, identifying 22 strongly supported long-range dispersal events including interoceanic and interhemispheric movement. Despite this propensity for geographic dispersal, the increased sampling of this study uncovered very few potential examples of ancestral dispersal among ecotypes. Concordance of nuclear and mitochondrial data further confirms genetic cohesiveness, with little or no current gene flow among sympatric ecotypes. Taken as a whole, our data suggest that the glacial cycles influenced local populations in different ways, with no clear global pattern, but with secondary contact among lineages following long-range dispersal as a potential mechanism driving ecological diversification.

opencc-zeroDec 2014View details →

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Data from: Post-fire response and genetic diversity in Erica coccinea: connecting population dynamics and diversification in a biodiversity hotspot

Understanding the proceses of biological diversification is a central topic in evolutionary biology. The South African Cape fynbos, one of the major plant biodiversity hotspots out of the tropics, has prompted several hypotheses about the causes of generation and maintenance of biodiversity. Fire has been traditionally invoked as a key element to explain high levels of biodiversity in highly speciose fynbos taxa, such as the genus Erica. In this study, we have implemented a microevolutionary approach to elucidate how plant-response to fire may contribute to explain high levels of diversification in Erica. By using microsatellite markers, we investigated the genetic background of seeder (fire-sensitive) and resprouter (fire-resistant) populations of the fynbos species Erica coccinea. We found higher within-population genetic diversity and higher among-population differentiation in seeder populations and interpreted these higher levels of genetic diversification as a consequence of the comparatively shorter generation times and faster population turnover in the seeder form of this species. Considering that genetic divergence among populations may be seen as the initial step to speciation, the parallelism between these results and the pattern of biodiversity at the genus level offers stimulating insights into understanding causes of speciation of the genus Erica in the Cape fynbos.

opencc-zeroDec 2009View details →

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Diversification dynamics in the Neotropics through time, clades and biogeographic regions

The origins and evolution of the outstanding Neotropical biodiversity are a matter of intense debate. A comprehensive understanding is hindered by the lack of deep-time comparative data across wide phylogenetic and ecological contexts. Here, we quantify the prevailing diversification trajectories and drivers of Neotropical diversification in a sample of 150 phylogenies (12,512 species) of seed plants and tetrapods and assess their variation across Neotropical regions and taxa. Analyses indicate that Neotropical diversity has mostly expanded through time (70% of the clades), while scenarios of saturated and declining diversity account for 21% and 9% of Neotropical diversity, respectively. Five biogeographic areas are identified as distinctive units of long-term Neotropical evolution, including Pan-Amazonia, the Dry Diagonal, and Bahama-Antilles. Diversification dynamics do not differ across these areas, suggesting no geographic structure in long-term Neotropical diversification. In contrast, diversification dynamics differ across taxa: plant diversity mostly expanded through time (88%), while a substantial fraction (43%) of tetrapod diversity accumulated at a slower pace or declined toward the present. These opposite evolutionary patterns may reflect different capacities for plants and tetrapods to cope with past climate changes

opencc-zeroNov 2022View details →

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Explosive Cenozoic origin and diversity-dependent diversification dynamics shaped the evolution of Australian skipper butterflies

Australia was predominantly tropical for most of the early Cenozoic, then transitioned to a cooler and drier climate in the Oligocene. In response to this increasing aridity, some lineages adapted to more xeric ecosystems, contracted, or became restricted to increasingly fragmented mesic refugia, or went extinct. Yet, the lack of macroevolutionary studies at a continental scale precludes a better understanding of Australian biodiversity patterns and processes during the Cenozoic. Here, we infer a robust dated phylogenomic tree for a radiation of Australian endemic butterflies, the Trapezitinae skippers, to test the impact of biotic and abiotic drivers on Cenozoic diversification dynamics in Australia. These butterflies originated during the Eocene (ca. 42 Ma) in the mesic biome of Australia. Trapezitinae exploded in diversity during a cool, dry period in the late Oligocene and early Miocene, then experienced a sharp deceleration in speciation. Xeric ecosystems appear to have been colonized more recently, supporting the hypothesis of arid and semi-arid biomes as evolutionary sinks. Temperature-dependent and phytophagy-dependent diversification models received little support. Instead, we find evidence for diversity-dependent processes with a declining diversification in Trapezitinae likely linked to limited ecological opportunities following a rapid initial burst of diversification.

opencc-zeroJan 2023View details →

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