scholarly journals Reproductive isolation among three populations of the genus Grammostola from Uruguay (Araneae, Theraphosidae)

2006 ◽  
Vol 96 (1) ◽  
pp. 71-74 ◽  
Author(s):  
Rodrigo Postiglioni ◽  
Fernando G. Costa
Keyword(s):  
Reproductive Isolation ◽  
Southern Population ◽  
Northern Population ◽  
Laboratory Conditions ◽  
Ethological Isolation ◽  
Two Populations ◽  
Isolated Species

Ethological isolation of individuals from three allopatric Grammostola populations of Uruguay, G. iheringi (Keyserling, 1891), G. mollicoma (Auserer, 1875) northern population and G. mollicoma southern population, was tested under laboratory conditions. Grammostola iheringi behaved as a reproductive isolated species, whereas the two populations of G. mollicoma did not show ethological isolation between them. However, ecological isolating reproductive mechanisms could be acting on G. mollicoma populations. Artificial burrows seem to be important for reproductive isolation in these species.

scholarly journals Male parental investment reflects the level of partner contributions and brood value in tree swallows

2017 ◽  
Author(s):  
Ádám Z. Lendvai ◽  
Çağlar Akçay ◽  
Mark Stanback ◽  
Mark F. Haussmann ◽  
Ignacio T. Moore ◽  
...  
Keyword(s):  
Parental Care ◽  
Interesting Case ◽  
Temporary Increase ◽  
Southern Population ◽  
Tree Swallows ◽  
Parental Effort ◽  
Northern Population ◽  
Nestling Begging ◽  
Two Populations ◽  
Partial Compensation

AbstractBiparental care presents an interesting case of cooperation and conflict between unrelated individuals. Several models have been proposed to explain how parents should respond to changes in each other’s parental care to maximize their own fitness, predicting no change, partial compensation, or matching effort as a response. Here, we present an experiment in tree swallows (Tachycineta bicolor) in which we increased the parental care of females by presenting them, but not their mates, with additional nestling begging calls using automated playbacks. We performed this experiment in two populations differing in future breeding opportunities and thus the intensity of conflict over current parental care. We found that in response to a temporary increase in female parental effort, males in the northern population with lower sexual conflict matched the increased effort, whereas males in the southern population did not. We also found that increases in parental care during playbacks were driven by the females (i.e., females initiated the increased effort and their mates followed them) in the northern population but not the southern population. These results support the idea that with incomplete information about the brood value and need, cues or signals from the partner might become important in coordinating parental care.

scholarly journals Dietary analysis of an uncharacteristic population of the Mountain Pygmy-possum(Burramys parvus)in the Kosciuszko National Park, New South Wales, Australia

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6307 ◽  
Author(s):  
Tahneal Hawke ◽  
Hayley Bates ◽  
Suzanne Hand ◽  
Michael Archer ◽  
Linda Broome
Keyword(s):  
Seasonal Variation ◽  
National Park ◽  
Climatic Variability ◽  
Critically Endangered ◽  
Conservation Strategies ◽  
Dietary Composition ◽  
Southern Population ◽  
Northern Population ◽  
Dietary Analysis ◽  
Critically Endangered Species

BackgroundThe Mountain Pygmy-possum (Burramys parvus) is a critically endangered marsupial, endemic to alpine regions of southern Australia. We investigated the diet of a recently discovered population of the possum in northern Kosciuszko National Park, NSW, Australia. This new population occurs at elevations well below the once-presumed lower elevation limit of 1,600 m.Goals and MethodsFaecal material was analysed to determine if dietary composition differed between individuals in the newly discovered northern population and those in the higher elevation southern population, and to examine how diet was influenced by rainfall in the southern population and seasonal changes in resource availability in the northern population.Results and DiscussionThe diet ofB. parvusin the northern population comprised of arthropods, fruits and seeds. Results indicate the diet of both populations shares most of the same invertebrate orders and plant species. However, in the absence of preferred food types available to the southern population, individuals of the northern population opportunistically consumed different species that were similar to those preferred by individuals in higher altitude populations. Differing rainfall amounts had a significant effect on diet, with years of below average rainfall having a greater percentage composition and diversity of invertebrates. Seasonal variation was also recorded, with the northern population increasing the diversity of invertebrates in their diet during the Autumn months when Bogong Moths (Agrotis infusa) were absent from those sites, raising questions about the possum’s dependence on the speciesConclusionsMeasurable effects of rainfall amount and seasonal variation on the dietary composition suggest that predicted climatic variability will have a significant impact on its diet, potentially impacting its future survival. Findings suggest that it is likely thatB. parvusis not restricted by dietary requirements to its current pattern of distribution. This new understanding needs to be considered when formulating future conservation strategies for this critically endangered species.

scholarly journals Assessing the role of two populations of Aedes japonicus japonicus for Zika virus transmission under a constant and a fluctuating temperature regime

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Uros Glavinic ◽  
Jasmin Varga ◽  
Anca Ioana Paslaru ◽  
Jeannine Hauri ◽  
Paul Torgerson ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Temperature Regime ◽  
Zika Virus ◽  
Incubation Temperature ◽  
Transmission Rate ◽  
Control Measures ◽  
Fluctuating Temperature ◽  
Laboratory Conditions ◽  
Temperature Regimes ◽  
Two Populations

Abstract Background Since the huge epidemic of Zika virus (ZIKV) in Brazil in 2015, questions were raised to understand which mosquito species could transmit the virus. Aedes aegypti has been described as the main vector. However, other Aedes species (e.g. Ae. albopictus and Ae. japonicus) proven to be competent for other flaviviruses (e.g. West Nile, dengue and yellow fever), have been described as potential vectors for ZIKV under laboratory conditions. One of these, the Asian bush mosquito, Ae. japonicus, is widely distributed with high abundances in central-western Europe. In the present study, infection, dissemination and transmission rates of ZIKV (Dak84 strain) in two populations of Ae. japonicus from Switzerland (Zürich) and France (Steinbach, Haut-Rhin) were investigated under constant (27 °C) and fluctuating (14–27 °C, mean 23 °C) temperature regimes. Results The two populations were each able to transmit ZIKV under both temperature regimes. Infectious virus particles were detected in the saliva of females from both populations, regardless of the incubation temperature regime, from 7 days post-exposure to infectious rabbit blood. The highest amount of plaque forming units (PFU) (400/ml) were recorded 14 days post-oral infection in the Swiss population incubated at a constant temperature. No difference in terms of infection, dissemination and transmission rate were found between mosquito populations. Temperature had no effect on infection rate but the fluctuating temperature regime resulted in higher dissemination rates compared to constant temperature, regardless of the population. Finally, transmission efficiency ranged between 7–23% and 7–10% for the constant temperature and 0–10% and 3–27% under fluctuating temperatures for the Swiss and the French populations, respectively. Conclusions To the best of our knowledge, this is the first study confirming vector competence for ZIKV of Ae. japonicus originating from Switzerland and France at realistic summer temperatures under laboratory conditions. Considering the continuous spread of this species in the northern part of Europe and its adaptation at cooler temperatures, preventative control measures should be adopted to prevent possible ZIKV epidemics.

scholarly journals The limits to parapatric speciation 3: evolution of strong reproductive isolation in presence of gene flow despite limited ecological differentiation

2020 ◽  
Vol 375 (1806) ◽  
pp. 20190532 ◽  
Author(s):  
Alexandre Blanckaert ◽  
Claudia Bank ◽  
Joachim Hermisson
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Theme Issue ◽  
Genetic Barrier ◽  
Incipient Species ◽  
Postzygotic Reproductive Isolation ◽  
Minimal Configuration ◽  
Parapatric Speciation ◽  
Two Populations

Gene flow tends to impede the accumulation of genetic divergence. Here, we determine the limits for the evolution of postzygotic reproductive isolation in a model of two populations that are connected by gene flow. We consider two selective mechanisms for the creation and maintenance of a genetic barrier: local adaptation leads to divergence among incipient species due to selection against migrants, and Dobzhansky–Muller incompatibilities (DMIs) reinforce the genetic barrier through selection against hybrids. In particular, we are interested in the maximum strength of the barrier under a limited amount of local adaptation, a challenge that many incipient species may initially face. We first confirm that with classical two-locus DMIs, the maximum amount of local adaptation is indeed a limit to the strength of a genetic barrier. However, with three or more loci and cryptic epistasis, this limit holds no longer. In particular, we identify a minimal configuration of three epistatically interacting mutations that is sufficient to confer strong reproductive isolation. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers’.

scholarly journals Hunter-gatherer adaptions during the Early Holocene in Northern Sweden

The Holocene ◽  
2020 ◽  
Vol 31 (1) ◽  
pp. 83-94
Author(s):  
Therese Ekholm
Keyword(s):  
Ice Sheet ◽  
The Other ◽  
Early Holocene ◽  
Taiga Zone ◽  
Southern Population ◽  
Northern Sweden ◽  
The West ◽  
Northern Population ◽  
Long Time ◽  
Sea Mammals

This paper deals with the study of the ecology of early Holocene, 9000-4000 cal BC, specifically human and faunal dispersal into the Norrland and Dalarna areas of northern Sweden. It has been hypothesised that this region of Sweden was settled by hunter-gatherer groups of Butovo/Veretye ancestry moving in from the eastern taiga zone and at the same time groups from the West Scandinavian coast were moving north following the melting Weichselian ice sheet. Due to the speed of the melting ice these two groups must have encountered each other in the central part of northern Sweden. This article discusses the environment of these two separate groups and the possible consequences of their encounter, informed by results from the zooarchaeological analysis of burnt, radiocarbon dated bones from sites spanning much of Norrland and Dalarna. A compilation of previously dated sites are presented, and also new 14C dates from excavated sites. The northern population preferred to hunt forest game and held on to it for a long time even if sea mammals were available. The southern population, on the other hand, hunted sea mammals and forest game through the whole period.

Latitudinal variation in Dendroctonus ponderosae (Coleoptera: Scolytidae) development time and adult size

2001 ◽  
Vol 133 (3) ◽  
pp. 375-387 ◽  
Author(s):  
B.J. Bentz ◽  
J.A. Logan ◽  
J.C. Vandygriff
Keyword(s):  
Pinus Ponderosa ◽  
Native Species ◽  
Development Time ◽  
Second Generation ◽  
Dendroctonus Ponderosae ◽  
Offspring Size ◽  
Adult Size ◽  
Southern Population ◽  
Northern Population ◽  
Generation Offspring

AbstractDendroctonus ponderosae (Hopkins) is widely distributed across western North America, feeding in at least 12 native species of Pinus L. (Pinaceae). We investigated the existence of heritable differences in two life-history parameters (adult size and development time) of D. ponderosae from a northern population (central Idaho, Pinus contorta Douglas ex Loudon) and a southern population (southern Utah, Pinus ponderosa Douglas ex P. and C. Lawson). We attempted to separate heritable from environmental effects by rearing individuals from both populations through two generations (F1 and F2) in a common standardized laboratory environment with a constant temperature. Two treatment effects were tested for in the F2 generation: (1) geographic location (source host) for F0D. ponderosae; and (2) the F2 brood host. We hypothesized that, if differences were observed and the F0 source host and region had a greater effect on F2 brood development time and adult size than did the host in which F2 brood were reared, a heritable factor related to the F0 parents was responsible. Time to emergence was significantly shorter for second-generation offspring of the northern population than for second-generation offspring of the southern population, regardless of the F2 brood host. Although both the F2 brood host and F0 source parents were significant in explaining differences observed in the developmental-time distribution of F2 brood, the F0 source effect was found to be much greater. Also, F2 males and females from southern source parents were significantly larger than F2 brood from northern source parents when reared in both F2 brood hosts. Geographic region and original host of F0 source parents had a significant effect on F2 offspring size, whereas the immediate food for F2 brood was not significant in explaining differences. These results suggest genetically based regional differences in D. ponderosae populations.

scholarly journals Phenotypic divergence during speciation is inversely associated with differences in seasonal migration

2015 ◽  
Vol 282 (1819) ◽  
pp. 20151921 ◽  
Author(s):  
Kira E. Delmore ◽  
Haley L. Kenyon ◽  
Ryan R. Germain ◽  
Darren E. Irwin
Keyword(s):  
Reproductive Isolation ◽  
Migratory Birds ◽  
Distinct Species ◽  
Seasonal Migration ◽  
Phenotypic Traits ◽  
Phenotypic Differentiation ◽  
Single Form ◽  
Breeding Grounds ◽  
Migratory Routes ◽  
Two Populations

Differences in seasonal migration might promote reproductive isolation and differentiation by causing populations in migratory divides to arrive on the breeding grounds at different times and/or produce hybrids that take inferior migratory routes. We examined this question by quantifying divergence in song, colour, and morphology between sister pairs of North American migratory birds. We predicted that apparent rates of phenotypic differentiation would differ between pairs that do and do not form migratory divides. Consistent with this prediction, results from mixed effects models and Ornstein–Uhlenbeck models of evolution showed different rates of divergence between these groups; surprisingly, differentiation was greater among non-divide pairs. We interpret this finding as a result of variable rates of population blending and fusion between partially diverged forms. Ancient pairs of populations that subsequently fused are now observed as a single form, whereas those that did not fuse are observable as pairs and included in our study. We propose that fusion of two populations is more likely to occur when they have similar migratory routes and little other phenotypic differentiation that would cause reproductive isolation. By contrast, pairs with migratory divides are more likely to remain reproductively isolated, even when differing little in other phenotypic traits. These findings suggest that migratory differences may be one among several isolating barriers that prevent divergent populations from fusing and thereby increase the likelihood that they will continue differentiating as distinct species.

scholarly journals Spiraling Complexity: A Test of the Snowball Effect in a Computational Model of RNA Folding

2016 ◽  
Author(s):  
Ata Kalirad ◽  
Ricardo B. R. Azevedo
Keyword(s):  
Reproductive Isolation ◽  
Computational Model ◽  
Genetic Divergence ◽  
Rna Folding ◽  
Fitness Landscape ◽  
Natural Populations ◽  
Using Data ◽  
Two Populations ◽  
Snowball Effect

ABSTRACTGenetic incompatibilities can emerge as a by-product of genetic divergence. According to Dobzhansky and Muller, an allele that fixes in one population may be incompatible with an allele at a different locus in another population when the two alleles are brought together in hybrids. Orr showed that the number of Dobzhansky–Muller incompatibilities (DMIs) should accumulate faster than linearly—i.e., snowball—as two lineages diverge. Several studies have attempted to test the snowball effect using data from natural populations. One limitation of these studies is that they have focused on predictions of the Orr model but not on its underlying assumptions. Here we use a computational model of RNA folding to test both predictions and assumptions of the Orr model. Two populations are allowed to evolve in allopatry on a holey fitness landscape. We find that the number of inviable introgressions (an indicator for the number of DMIs) snowballs, but does so more slowly than expected. We show that this pattern is explained, in part, by the fact that DMIs can disappear after they have arisen, contrary to the assumptions of the Orr model. This occurs because DMIs become progressively more complex (i.e., involve alleles at more loci) as a result of later substitutions. We also find that most DMIs involve more than two loci—i.e., they are complex. Reproductive isolation does not snowball because DMIs do not act independently of each other. We conclude that the RNA model supports the central prediction of the Orr model that the number of DMIs snowballs, but challenges other predictions, as well as some of its underlying assumptions.

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