Abbott R.,University of St. Andrews |
Albach D.,Carl von Ossietzky University |
Ansell S.,Natural History Museum in London |
Arntzen J.W.,Netherlands Center for Biodiversity Naturalis |
And 36 more authors.
Journal of Evolutionary Biology | Year: 2013
Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near-instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky-Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock-on effects on speciation both within and outside regions of hybridization. © 2013 European Society For Evolutionary Biology.
PubMed | ICBAS., CIBIO., Uppsala University, CIBIO; and 2 more.
Type: | Journal: Genetics | Year: 2016
The dwarf phenotype characterizes the smallest of rabbit breeds and is governed largely by the effects of a single dwarfing allele with an incompletely dominant effect on growth. Dwarf rabbits typically weigh under 1 kg and have altered craniofacial morphology. The dwarf allele is a recessive lethal and dwarf homozygotes die within a few days of birth. The dwarf phenotype is expressed in heterozygous individuals and rabbits from dwarf breeds homozygous for the wild-type allele are normal, although smaller when compared to other breeds. Here, we show that the dwarf allele constitutes a ~12.1 kb deletion overlapping the promoter region and first three exons of the HMGA2 gene leading to inactivation of this gene. HMGA2 has been frequently associated with variation in body size across species. Homozygotes for null alleles are viable in mice but not in rabbits and probably not in humans. RNA-seq analysis of rabbit embryos showed that very few genes (4-29 genes) were differentially expressed among the three HMGA2/dwarf genotypes, suggesting that dwarfism and inviability in rabbits are caused by modest changes in gene expression. Our results show that HMGA2 is critical for normal expression of IGF2BP2, which encodes an RNA-binding protein. Finally, we report a catalog of regions of elevated genetic differentiation between dwarf and normal-size rabbits, including LCORL-NCAPG, STC2, HOXD cluster, and IGF2BP2 Levels and patterns of genetic diversity at the LCORL-NCAPG locus further suggest that small size in dwarf breeds was enhanced by crosses with wild rabbits. Overall, our results imply that small size in dwarf rabbits results from a large effect, loss-of-function mutation in HMGA2 combined with polygenic selection.
Segurado P.,CIBIO |
Segurado P.,University of Lisbon |
Kunin W.E.,University of Leeds |
Filipe A.F.,University of Lisbon |
And 3 more authors.
Basic and Applied Ecology | Year: 2012
Inferring biotic interactions from the examination of patterns of species occurrences has been a central tenet in community ecology, and it has recently gained interest in the context of single-species distribution modelling. However, understanding of how spatial extent and grain size affect such inferences remains elusive. For example, would inferences of biotic interactions from broad-scale patterns of coexistence provide a surrogate for patterns at finer spatial scales? In this paper we examine how the spatial and environmental association between two closely related species of freshwater turtles in the Iberian Peninsula is affected by the geographical extent and resolution of the analysis. Species coexistence was compared across spatial scales using five datasets at varying spatial extents and resolutions. Both similarities in the two species' use of space and in their responses to environmental variables were explored by means of regression analyses. We show that a positive association between the two species measured at broader scales can switch to a negative association at finer scales. We demonstrate that without examination of the effects of spatial scale when investigating biotic interactions using co-occurrence patterns observed at coarse resolutions, conclusions can be deeply misleading. © 2012 Gesellschaft für ökologie.
News Article | November 6, 2015
A multidisciplinary research team made up of researchers from the Spanish universities of Alicante, Jaen and Granada, the French universities of Montpellier and Paul-Valéry Montpellier, CSIC's National Museum of Natural Sciences and the IUCN Centre for Mediterranean Cooperation has analysed the impact of ivermectin on Scarabaeus cicatricosus populations in the Mediterranean. Led by José R. Verdú from the Ibero-American Centre for Biodiversity (CIBIO) at the Universidad de Alicante (University of Alicante, UA), this research shows that arthropods that ingest this substance, even in low doses, become unable to interact with their surroundings since it affects both their olfactory and locomotor capacity. This fact may explain the population decline observed for this dung beetle. The article "Low doses of Ivermectin cause sensory and musculoskeletal disorders in dung beetles" was published in Scientific Reports in September. Ivermectin is a very effective anti-parasitic drug that has been used as a preventative in livestock since its discovery in 1981. Since then its use has increased exponentially to become a standard drug in the treatment and prevention of common parasites, including in human beings. Considered by the World Health Organization as an essential medication, Verdú points out that, although this drug has proven very effective, its widespread use comes at a price. The issue, researchers have found, is that the ivermectin molecule can survive its journey through the animal and be excreted unchanged. Also, once on the ground, residues can remain active in animal dung for at least a month. This means the drug hits the arthropod populations as hard as it does the parasites it is intended to prevent. It is in this context that Verdú's team draws attention to the declining beetle populations, reporting that the ingestion of ivermectin affects even mature dung beetles, seriously compromising their mobility, orientation and reproductive capacities. These findings contradict international veterinary manuals and yet offer an explanation for thedecline in population levels reported in other research. For this study, researchers used electroantennography, olfactometry and muscle force tests for the first time to obtain measures of the insects' sensory and muscle power. It was carried out in the Doñana Natural Park in southern Spain, testing specimens taken from protected, ivermectin-free sites and land where ivermectin is used. Different rates of decomposition of dung were observed between the two sites, rates being some 30 percent lower in the sites where ivermectin was used. This can be ascribed to the absence of dung beetles as, without them, dung accumulates in the field unprocessed. With populations of beneficial dung feeder species declining over the past 20 to 30 years, "the difference between land with beetles and land without is the difference between roughly 350 kilograms of dung per hectare per year that is not being buried in areas affected by ivermectin", the researcher said. So aside from the lethal and sub-lethal effects of ivermectin on dung feeders, the use of this drug has a knock-on effect on the quality of the pasture for livestock, not to mention the irreparable loss of biodiversity in Mediterranean ecosystems. A further consequence is the growth of highly nitrophilous plants, which again are no good for livestock grazing. Researchers also speculate that ivermectin may be present in the food chain, pointing to the insectivorous birds that feed on dung beetles. More information: José R. Verdú et al. Low doses of ivermectin cause sensory and locomotor disorders in dung beetles, Scientific Reports (2015). DOI: 10.1038/srep13912
Gracia E.,University Miguel Hernández |
Botella F.,University Miguel Hernández |
Anadon J.D.,CSIC - Doñana Biological Station |
Anadon J.D.,Arizona State University |
And 4 more authors.
Biology Letters | Year: 2013
Much of our current knowledge about the genetic dynamics in range expansions originates from models, simulations and microcosm experiments that need to be corroborated by field data. Here,we report a neutral genetic pattern that matches the predictions of the genetic surfing theory. Genetic surfing occurs when repeated founding events and genetic drift act on the wave of advance of an expanding population, promoting strong spatial structure. In the range expansion of the tortoise Testudo graeca from North Africa to southeastern Spain, we found several genetic signatures consistent with surfing: a decrease of genetic diversity with distance from the initial founder area, clinal patterns in allele frequencies, rare African alleles which have become common at distal sites in the Spanish range, and stronger spatial differentiation in the expanded range than in the original one. Our results provide support for the theory that genetic drift can be an important force in shaping the genetic structure of expanding populations. © 2013 The Author(s) Published by the Royal Society.
Gracia E.,University Miguel Hernández |
Gimenez A.,University Miguel Hernández |
Anadon J.D.,University Miguel Hernández |
Harris D.J.,CIBIO |
And 2 more authors.
Journal of Biogeography | Year: 2013
Aim: Recent biogeographical studies have postulated a North African, Late Pleistocene, origin for some species of the Iberian Peninsula. However, a robust assessment of such range expansions requires high-resolution molecular tools to resolve overlapping biogeographical and cultural processes. Here we aim to determine whether the spur-thighed tortoise, Testudo graeca, arrived in south-eastern Spain during historical or prehistoric times, and whether its dispersal to the Iberian Peninsula was human-mediated. Location: The western Mediterranean Basin (south-eastern Spain, northern Algeria and north-western Morocco). Methods: Using 428 samples from 19 sites in North Africa and 18 in south-eastern Spain, we obtained mitochondrial sequences from the cytochrome b gene and genotypes derived from seven microsatellite loci. These data were employed to obtain population genetics descriptors, haplotype networks, Bayesian cluster analyses and isolation-by-distance patterns. Moreover, we used a Bayesian demographic approach to delimit the dates involved in the range expansion. Results: We found lower levels of genetic variability and weak mitochondrial differentiation in the south-eastern Spanish tortoises compared with the North African ones. However, exclusive haplotypes occurred in the Iberian samples and microsatellite cluster analyses revealed moderate levels of admixture across both sides of the Mediterranean. A coastal area in the west of Algeria and the central-southern region in south-eastern Spain are suggested as the most probable founder and arrival places, respectively. Finally, we identified signatures of an ancient bottleneck event approximately 20,000-30,000 years ago. Main conclusions: The spur-thighed tortoise probably arrived in south-eastern Spain during Late Pleistocene sea-level low stands. The role that humans may have played as dispersers across the Mediterranean remains unclear. Our results are in accordance with other recent findings of trans-Mediterranean expansions during this period and highlight the importance of employing precise methodological approaches before a species can be considered as historically introduced. © 2012 Blackwell Publishing Ltd.
Visnevschi-Necrasov T.,CIBIO |
Visnevschi-Necrasov T.,University of Porto |
Harris D.J.,CIBIO |
Faria M.A.,Laboratory of Food and Water Science |
And 3 more authors.
Spanish Journal of Agricultural Research | Year: 2012
Genetic diversity within Iberian populations of Ornithopus pinnatus, O. compressus, O. sativus and Biserrula pelecinus were assessed using ITS1 and ITS2 DNA sequences from sixty four specimens, and a phylogeny between Ornithopus species was estimated. Generally within-species variation was low, particularly within Ornithopus. The Mediterranean species of Ornithopus form a sister clade relative to the South American O. micranthopus. The sometimes considered a full species, O. sativus isthmocarpus, was not distinct from O. sativus. Between some species there is limited genetic divergence using these markers, although the situation of O. perpusillus requires additional specimens to be examined before firm conclusions can be drawn.
News Article | October 5, 2016
That heap of hay in a tree is not a typical animal commune. Huge group nests of sociable weaver birds across southern Africa are about as close as nature gets to building condos. Ant nests, beaver lodges and many other marvels of animal architecture enclose shared space. But small, sparrowlike Philetairus socius push together beakful after beakful of grass to create a haystack of apartments. The nests can grow to weigh a ton and last about a century. Tunnels opening from the shaggy underside lead to each family’s unit. For better and worse, a weaver bird nest “in practice is like a block of flats,” says evolutionary biologist Rita Covas of CIBIO Research Center at the University of Portugal. The condos have great insulation, an important perk for birds that don’t migrate from the hot-then-cold Kalahari. In summer, Covas can feel shady relief when she reaches up into a nest. In winter, condos are heated by snuggle power. The thatch keeps a chamber with a lone bird at about 12° Celsius. An apartment crowded with five birds reaches a toasty 33° C, Covas and colleagues reported in June in the Journal of Avian Biology. An apartment can fill up as a few young birds linger for a gap year before venturing away. The stay-at-homes pitch in to hunt food for the newest nestlings. The help lets parents ease off a bit in foraging, though oddly enough, mom’s life lengthens when her offspring stay close while dad’s tends to shorten. Why is still a puzzle. Even with help, raising chicks is chancy when a nest offers a feast for marauders. “Those poor birds,” Covas says. “Snakes climb the trees to get into the colony and then they inspect every single chamber — they’re very thorough.” Adult weavers will mob loudly and frantically, but a cape cobra or boomslang ignores them, bingeing on eggs and chicks by the dozen. The birds can cause trouble for each other, too. “There are lots of chases,” Covas says. Outright murder is rare, but during food shortages, a neighbor on occasion pushes into the chamber next door and kills the chicks for causes still unknown. “Reducing competition?” Covas speculates. “Spite?”