An official website of the United States government
ABSTRACT AimInsect brood parasites (i.e., cleptoparasites), like cuckoo bees, typically attack hosts within specific lineages, but seem to be less constrained by the biogeographical movements of their hosts compared to obligate parasites. Cuckoo bees depend on stable host populations, being particularly sensitive to environmental changes and thus valuable bioindicators of the bee community health. We here test the congruence between the biogeographical history of cuckoo oil bees and their oil bee hosts. LocationThe Americas. TaxonBees (Hymenoptera, Apidae). MethodsUsing phylogenomic and Sanger sequence data, we present new time‐calibrated phylogenies for cuckoo oil bees in the ericrocidine line and their oil bee hosts,CentrisandEpicharis.We estimate their ancestral ranges using six historical biogeographical models on a set of 100 trees, randomly sampled from the posterior distribution of phylogenies in each group, thus accounting for uncertainties in divergence time estimates and model selection. ResultsThe origin of the hosts stem in the Cretaceous precedes the origin of their cleptoparasite's stem in the Palaeocene. Cleptoparasite and host crown origins were synchronous in the Eocene, and both took place in tropical South America. While the pair Rhathymini‐Epicharisremained mostly associated within this region,Centrisand their cleptoparasites expanded their distribution to other parts of Neotropical and Nearctic regions in independent range expansions events. In all cases, host range shifts preceded the cleptoparasite shifts. Main ConclusionThe biogeographical history of cleptoparasitic oil bees and oil‐collecting hosts is generally congruent in time and space. Events of range expansion mainly occurred in the more species‐rich lineages of cleptoparasites. Range shifts in cleptoparasites followed the distribution of their hosts and coincided with the distribution of oil‐producing plants visited by the host bees. Our results broaden our understanding of the complex biogeography of interacting partners and on how changes in host distributions may impact cleptoparasitic bees.
more »
« less
Phylogenomic dating and Bayesian biogeography illuminate an antitropical pattern for eucerine bees
Abstract AimAn antitropical pattern is characterized by the occurrence of closely related taxa south and north of the tropics but absent or uncommonly represented closer to the equator, in contrast to most taxa, which tend to have their highest diversity in the tropical regions. We investigate the antitropical distribution of eucerine bees with the aim of contributing to the characterization and understanding of this pattern. LocationAll continents except Antarctica and Australia. TaxonEucerine bees (Hymenoptera: Apidae: Eucerinae). MethodsWe carried out phylogenomic dating under two different clock models and used multiple strategies to vary matrix composition, evaluating the overlapping of divergence times estimated across models using Bhattacharyya coefficients. Lastly, we reconstructed the biogeographic history of eucerine bees using a Bayesian implementation of the DEC model. ResultsEucerinae is estimated to have started diversifying during the Palaeocene, with all its tribes originating during the Palaeocene/Eocene transition in southern South America. At least two range expansions happened into North America before the full closure of the Isthmus of Panama. We show that divergence between closely related groups with disjunct distributions would have happened in periods when the climate favoured the expansion of open habitats and became isolated when the forests were re‐established. Main conclusionsWe describe the early diversification of eucerine bees, revealing an intimate association with southern South America. Events of range evolution of Eucerinae were likely affected by periods of global cooling and aridification, and palaeoclimatic and vegetational conditions probably have been more relevant to the formation of the antitropical distribution of Eucerinae than the consolidation of the Isthmus of Panama connecting the Americas. We also demonstrate that most uncertainty in divergence time estimation is not due to the amount of molecular data being used, but more likely other factors like fossil calibrations and violations of clock models.
more »
« less
- Award ID(s):
- 2127744
- PAR ID:
- 10369022
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Biogeography
- Volume:
- 49
- Issue:
- 6
- ISSN:
- 0305-0270
- Format(s):
- Medium: X Size: p. 1034-1047
- Size(s):
- p. 1034-1047
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
ABSTRACT AimThuridillaBergh, 1872, is a lineage of herbivorous sea slugs externally distinguished by bright colours and distinctive patterns of lines and spots. Recent work revealed an exceptionally rapid, cryptic radiation of 13 species in the Indo‐Pacific, raising questions about mechanisms of speciation in this group. Here, we (i) study the diversification and historical biogeography ofThuridillain a phylogenetic context and (ii) assess the role of dispersal and vicariance as the predominant mode of speciation in the genus. LocationTropical and temperate regions of the Atlantic and Indo‐Pacific. Major Taxa StudiesGastropoda, Sacoglossa. MethodsA nearly complete taxon set with 28 out of 32 recognised species ofThuridillawas used, in a total sample of 172 specimens, together with sacoglossan outgroups. Phylogenetic relationships were determined using a multi‐locus approach combining two mitochondrial (COI and 16S) and one nuclear gene (H3). Species relationships, diversification times, and ancestral geographical ranges were inferred using relaxed‐clock methods together with Bayesian discrete phylogeographic methods under three calibration scenarios using the oldest known fossil of Sacoglossa,Berthelinia elegansCrosse, 1875, and tectonic events. ResultsThuridillaspecies branched off into four major clades in all calibration scenarios: two groups from the Atlantic plus Indo‐West Pacific (5 and 6 species) and two clades from the Indo‐West Pacific (4 and 17 species). The highest diversity of the genus is in the Western Pacific (14 spp.) with a peak in the East Indies Triangle (18 spp.), whereas the Atlantic is depauperate with only four species occurring in this ocean basin. Divergence between Atlantic and Indo‐West Pacific lineages occurred in two main temporal periods: the Miocene and the Pliocene. Speciation events within the 13 cryptic species‐complex fell mostly within Plio‐Pleistocene times. Main ConclusionsThe best supported hypothesis was an Indo‐West Pacific origin ofThuridillabetween 28 and 18 Mya during the Early Miocene. In the western Pacific, speciation likely occurred during transient allopatry during Plio‐Pleistocene sea‐level fluctuations. Under the three tested calibration scenarios, the limited diversity of the Atlantic Ocean is hypothesized to be derived from Miocene vicariant events associated with the closure of the Tethys Sea, dispersal across southern Africa, or long‐distance dispersal across the East Pacific Barrier prior to the uplift of the Isthmus of Panama.Thuridillais absent in the Eastern Pacific, potentially resulting from the extinction of ancestral lineages following the uplift of the Isthmus of Panama. Near‐complete sampling of diversity and reconstruction of historical biogeography thus yielded new insight into the relative contributions of dispersal versus vicariance during speciation over the history of this widely distributed, colourful genus.more » « less
-
Abstract AimWe explore the biogeographic history of the Gondwanan lineage Triaenonychidae, a dispersal‐limited arachnid taxon that underwent a recent taxonomic revision based on phylogenomic data. We explicitly test hypotheses related to a biogeographical pattern of ‘common vicariance, rare dispersal’, predicted for dispersal‐limited taxa. LocationContinental landmasses of former temperate Gondwanan terranes (southern South America, southern Africa, Madagascar, Australia, New Zealand, and New Caledonia). TaxonTriaenonychidae, Opiliones, Arachnida. MethodsUtilizing a recently published phylogenomic data set based on ultra‐conserved elements, we conduct Bayesian divergence dating analyses, ancestral area estimation in a likelihood model testing framework, and analyses of macroevolutionary dynamics. Results are correlated with geological history and palaeoclimate reconstructions to infer biogeographic history and distribution. ResultsWe find that divergence dates of ancestral Triaenonychidae pre‐date continental breakup of Gondwana and could be attributed to palaeoclimatic differentiation across Gondwana. There is evidence for two separate expansion routes that span eastern and western Gondwana corresponding to northern warmer climate and southern cooler climate lineages. Many divergences across intercontinental lineages coincide with the timing of continental fragmentation, supporting vicariance as a dominant force. However, some lineages are supported as obvious examples of rare long‐distance dispersal. Biogeographic results support the predicted pattern of common vicariance and rare dispersal for these dispersal‐limited organisms. Main conclusionsVicariance due to continental fragmentation was important in the early diversification of Triaenonychidae. Their unique combination and degrees of dispersal ability and microhabitat preference resulted in complex phylogenetic patterns of geographic distribution not typically seen in other animal taxa. Examining biogeographic patterns across recent studies of arachnid taxa with varying dispersal ability, it is clear that biological characteristics play an important role in the relative importance of dispersal and vicariance (dispersal–vicariance continuum) for any given taxon and can be useful in forming testable a priori hypotheses.more » « less
-
For nearly 30 years, biologists have documented a striking pattern of intra-species genetic divergence on the Baja California peninsula in dozens of disparate species. Evolutionary theory predicts that when such a pattern is shared among species the cause is extrinsic (e.g., environmental, climatic, physiographic, geological). The leading hypothesis within biological literature has been that genetic divergence was facilitated by flooding across the central peninsula by a seaway between ~3-1 Ma, resulting in separation of northern and southern populations. However, new detailed geologic mapping from the Baja GeoGenomics consortium reveals evidence for continuous terrestrial environments during the last ~30 Myr in a ≥40-km-wide ~E-W region of the central peninsula that straddles the modern-day crest, conclusively refuting the seaway hypothesis. Through integration of tectonic, volcanic, and sedimentological evidence with genomic (DNA) and gene expression (RNA) data for plants and animals, we are developing a new working model for Earth-life evolution on the peninsula over the last ~5 Myr. In this model, rift-related uplift drives the growth and dissection of topography, causing increased microenvironmental heterogeneity that populations differentially adapted to in the north and south. This is evidenced by widespread, statistically significant niche divergence in populations between northern and southern Baja in 21 studied taxa. This pattern is supported by strong differences in gene expression in northern and southern populations of two lizard species, particularly in genes relating to metabolism, which may indicate different diet or energy requirements between the regions. Habitats in the north and south then shifted due to glacial and interglacial periods, indicated by hindcasting the estimated niche conditions of those 21 taxa. With ongoing analyses, we expect to find genomic signatures of differential natural selection and adaptation within these species due in part to monsoon-driven rainfall differences. The significance of this work is twofold: it demonstrates the importance of incorporating geological data into evolutionary hypotheses and it cautions how mis-assigning cause-effect relationships in individual Earth-life systems can bias our fundamental understanding of how Earth processes shape biological evolution writ large.more » « less
-
Abstract AimIdentifying how climate change, habitat loss, and corridors interact to influence species survival or extinction is critical to understanding macro‐scale biodiversity dynamics under changing environments. In North America, the ice‐free corridor was the only major pathway for northward migration by megafaunal species during the last deglaciation. However, the timing and interplay among the late Quaternary megafaunal extinctions, climate change, habitat structure, and the opening and reforestation of the ice‐free corridor have been unclear. LocationNorth America. Time period15–10 ka. Major taxa studiedWoolly mammoth (Mammuthus primigenius). MethodsFor central North America and the ice‐free corridor between 15 and 10 ka, we used a series of models and continental‐scale datasets to reconstruct habitat characteristics and assess habitat suitability. The models and datasets include biophysical and statistical niche models Niche Mapper and Maxent, downscaled climate simulations from CCSM3 SynTraCE, LPJ‐GUESS simulations of net primary productivity (NPP) and woody cover, and woody cover based upon fossil pollen from Neotoma. ResultsThe ice‐free corridor may have been of limited suitability for traversal by mammoths and other grazers due to persistently low productivity by herbaceous plants and quick reforestation after opening 14 ka. Simultaneously, rapid reforestation and decreased forage productivity may have led to declining habitat suitability in central North America. This was possibly amplified by a positive feedback loop driven by reduced herbivory pressures, as mammoth population decline led to the further loss of open habitat. Main conclusionsDeclining habitat availability south of the Laurentide Ice Sheet and limited habitat availability in the ice‐free corridor were contributing factors in North American extinctions of woolly mammoths and other large grazers that likely operated synergistically with anthropogenic pressures. The role of habitat loss and attenuated corridor suitability for the woolly mammoth extinction reinforce the critical importance of protected habitat connectivity during changing climates, particularly for large vertebrates.more » « less
