Severe Habitat Fragmentation Leads to Declines in Genetic Variation, Mate Availability, and Reproductive Success in Small Populations of a Once-Common Australian Grassland Daisy

2013 ◽  
Vol 174 (9) ◽  
pp. 1209-1218 ◽  
Author(s):  
John W. Morgan ◽  
Michaela J. Meyer ◽  
Andrew G. Young
Keyword(s):  
Genetic Variation ◽  
Habitat Fragmentation ◽  
Reproductive Success ◽  
Small Populations ◽  
Mate Availability

scholarly journals Population size, habitat fragmentation, and the nature of adaptive variation in a stream fish

2014 ◽  
Vol 281 (1790) ◽  
pp. 20140370 ◽  
Author(s):  
Dylan J. Fraser ◽  
Paul V. Debes ◽  
Louis Bernatchez ◽  
Jeffrey A. Hutchings
Keyword(s):  
Genetic Variation ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Brook Trout ◽  
Small Populations ◽  
Adaptive Genetic Variation ◽  
Genetic Population ◽  
Fragmented Populations ◽  
Large Populations ◽  
Adaptive Differentiation

Whether and how habitat fragmentation and population size jointly affect adaptive genetic variation and adaptive population differentiation are largely unexplored. Owing to pronounced genetic drift, small, fragmented populations are thought to exhibit reduced adaptive genetic variation relative to large populations. Yet fragmentation is known to increase variability within and among habitats as population size decreases. Such variability might instead favour the maintenance of adaptive polymorphisms and/or generate more variability in adaptive differentiation at smaller population size. We investigated these alternative hypotheses by analysing coding-gene, single-nucleotide polymorphisms associated with different biological functions in fragmented brook trout populations of variable sizes. Putative adaptive differentiation was greater between small and large populations or among small populations than among large populations. These trends were stronger for genetic population size measures than demographic ones and were present despite pronounced drift in small populations. Our results suggest that fragmentation affects natural selection and that the changes elicited in the adaptive genetic composition and differentiation of fragmented populations vary with population size. By generating more variable evolutionary responses, the alteration of selective pressures during habitat fragmentation may affect future population persistence independently of, and perhaps long before, the effects of demographic and genetic stochasticity are manifest.

Effects of habitat fragmentation on population genetic structure in the white-footed mouse (Peromyscus leucopus)

2001 ◽  
Vol 79 (2) ◽  
pp. 285-295 ◽  
Author(s):  
Catherine A Mossman ◽  
Peter M Waser
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Habitat Fragmentation ◽  
Genetic Differentiation ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Peromyscus Leucopus ◽  
Marginal Effect ◽  
Geographic Scale ◽  
White Footed Mouse

Habitat fragmentation may have significant consequences for population genetic structure because geographic distance and physical barriers may impede gene flow. In this study, we investigated whether habitat fragmentation affects fine-scale genetic structure of populations of the white-footed mouse (Peromyscus leucopus). We studied 27 populations of P. leucopus, 17 in continuous forest and 10 in isolated woodlots. Populations were trapped in pairs that were either 500 or 2000 m apart. We estimated genetic variation at eight P. leucopus specific microsatellite DNA loci. We discovered significant genetic variation within all populations, but no significant differences in numbers of alleles or heterozygosity between populations. For given population pairs, we found significant genetic differentiation even at very short distances, based on multilocus FST estimates. The amount of genetic differentiation between population pairs was similar in the two habitats. Distance had a marginal effect on genetic differentiation when comparing paired populations separated by 2000 m with those separated by 500 m. However, at a larger geographic scale, there was no evidence of isolation by distance. This study confirms that microsatellite-based studies have the potential to detect interpopulation differentiation at an extremely local scale, and suggests that habitat fragmentation has surprisingly few effects on P. leucopus genetic structure.

scholarly journals Plasticity in probabilistic reaction norms for maturation in a salmonid fish

2009 ◽  
Vol 5 (5) ◽  
pp. 628-631 ◽  
Author(s):  
Kentaro Morita ◽  
Jun-ichi Tsuboi ◽  
Toru Nagasawa
Keyword(s):  
Genetic Variation ◽  
Body Size ◽  
Reproductive Success ◽  
Reaction Norm ◽  
Reaction Norms ◽  
Transplant Experiment ◽  
Size At Maturity ◽  
Threshold Size ◽  
Precocious Males ◽  
The Relationship

The relationship between body size and the probability of maturing, often referred to as the probabilistic maturation reaction norm (PMRN), has been increasingly used to infer genetic variation in maturation schedule. Despite this trend, few studies have directly evaluated plasticity in the PMRN. A transplant experiment using white-spotted charr demonstrated that the PMRN for precocious males exhibited plasticity. A smaller threshold size at maturity occurred in charr inhabiting narrow streams where more refuges are probably available for small charr, which in turn might enhance the reproductive success of sneaker precocious males. Our findings suggested that plastic effects should clearly be included in investigations of variation in PMRNs.

Invited Minireview: Restoring Demographic Processes in Translocated Populations: The Case of Collared Lizards in the Missouri Ozarks Using Prescribed Forest Fires

2007 ◽  
Vol 53 (2) ◽  
pp. 179-196 ◽  
Author(s):  
Alan R. Templeton ◽  
Jennifer L. Neuwald ◽  
Hilary Brazeal ◽  
R. James Robertson
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Habitat Fragmentation ◽  
Forest Fires ◽  
Local Extinction ◽  
Management Policy ◽  
Fire Scar ◽  
Local Populations ◽  
Collared Lizard ◽  
Rocky Habitats

Habitat fragmentation is one of the more important contributors to species endangerment, but one form of fragmentation, here called dispersal fragmentation, can often go unobserved for many years after it has occurred. Many species live in naturally fragmented habitats, but the local populations are interconnected genetically and demographically by dispersal through the environmental matrix in which the habitats are embedded. Because of dispersal, the local populations are not truly fragmented evolutionarily or ecologically. However, when human activities alter the environmental matrix such that dispersal is no longer possible, the population does indeed become fragmented even though they initially are present in the same habitats. An example of dispersal fragmentation via an altered environmental matrix is provided by the eastern collared lizard (Crotaphytus collaris collaris). This lizard lives on open, rocky habitats, called glades, that are embedded in the forests of the Ozarks, a highland region located primarily in Missouri and Arkansas in the USA. Forest fire suppression has reduced this habitat, resulting in severe habitat fragmentation, disruption of gene flow, loss of genetic variation within glade populations, and local extinction without recolonization. Beginning in 1982, glade habitats were restored by clearing and burning in the Peck Ranch area of the Missouri Ozarks, a region where the lizards had gone extinct. Starting in 1984, lizard populations were translocated from other Missouri glades onto restored glades at the Peck Ranch. Although these translocated populations survived well on the restored glades, no movement was detected between glades, some just 50 m apart, and no colonization of nearby restored glades, some just 60 m away, occurred between 1984 and 1993. Fragmentation, lack of colonization, no gene flow, and loss of genetic variation still persisted despite translocation reversing some of the local extinction. Fire scar data from trees and tree stumps indicated that forest fires were common in this area prior to European settlement, so in 1994 a new management policy of prescribed burning of both the glades and their forest matrix was initiated. Once the forest had been burned, the lizards could disperse kilometers through the forest, thereby reestablishing the processes of dispersal, gene flow, colonization, and local extinction followed by recolonization. This resulted in a dramatic increase in population size and inhabited area. By incorporating a landscape perspective into the management strategy, the eastern collared lizard has been successfully reestablished in a region of historic extirpation.

scholarly journals The role of APETALA1 in petal number robustness

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Marie Monniaux ◽  
Bjorn Pieper ◽  
Sarah M McKim ◽  
Anne-Lise Routier-Kierzkowska ◽  
Daniel Kierzkowski ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Genetic Variation ◽  
Reproductive Success ◽  
Genetic Basis ◽  
Phenotypic Expression ◽  
Specific Difference ◽  
Closely Related Species ◽  
Epistatic Interactions ◽  
Species Specific

Invariant floral forms are important for reproductive success and robust to natural perturbations. Petal number, for example, is invariant in Arabidopsis thaliana flowers. However, petal number varies in the closely related species Cardamine hirsuta, and the genetic basis for this difference between species is unknown. Here we show that divergence in the pleiotropic floral regulator APETALA1 (AP1) can account for the species-specific difference in petal number robustness. This large effect of AP1 is explained by epistatic interactions: A. thaliana AP1 confers robustness by masking the phenotypic expression of quantitative trait loci controlling petal number in C. hirsuta. We show that C. hirsuta AP1 fails to complement this function of A. thaliana AP1, conferring variable petal number, and that upstream regulatory regions of AP1 contribute to this divergence. Moreover, variable petal number is maintained in C. hirsuta despite sufficient standing genetic variation in natural accessions to produce plants with four-petalled flowers.

Sign in / Sign up

Export Citation Format

Share Document