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Three natural populations of Kinosternon scorpioides located in the region of Baixada Maranhense were studied in order to quantify and compare levels of diversity and genetic structure using SSR markers. Ten microsatellite loci were validated for analysis in 56 individuals. The observed heterozygosities (Ho) were 0.838; 0.691 and 0.741 and the expected (He) 0.824; 0.819 and 0.815 for the populations of São Bento, Pinheiro and Anajatuba, respectively. AMOVA test showed that 98.97% of the total genetic variation is within populations while 1.03% is among populations. The estimated gene flow of 6,882 corroborates the small population differentiation (FST = 0.044). The populations of São Bento and Pinheiro are closer together genetically, according to the presented grouping analysis. These genetic data are important for the elaboration of strategic actions of management and conservation of the chelonians and especially Kinosternon scorpioides. [ABSTRACT FROM AUTHOR]

In Romania, the GM commercial crops are limited to MON 810 corn that is resistant to the European corn borer (ECB, Ostrinia nubilalis). This GM corn is authorized for cultivation since 2007 (when Romania became a member of the European Union). To ensure the coexistence, the adventitious presence of the genetically modified organisms must not exceed the level of 0.9 % established by Regulation (EC) 1829/2003. Because the corn is a species with female and male flowers formed in separate parts of the same plant, the gene flow between plants is high. The pollen - mediated gene flow of corn can be monitored by measurement the rate of cross-pollination. The objective of this study was the cross-pollination rate between GM and conventional corn by xenia effect. For this, three experimental fields were established at ARDS Simnic. Within the first experience, where the MON 810 event was planted at the centre of the experimental field and surrounded by conventional corn as receiver, the rate of cross-pollination ranged from 0.83% (plot N-E) to 3.72% (plot W). Within the second experience, where the receiver corn was planted at the centre of the experimental field and surrounded by the donor MON 810, there was recorded the highest rate of cross - pollination, respectively of 27.62%. In a third experiment where they used different isolation distances, cross-pollination rates were between 1.40 and 1.74% for 10 - 19.8 m distance, between 0.77 and 0.94% for 20 - 29.8 m distance and between 0.90 and 0.94% for 30-30.8 m distance. The high levels of cross - pollination rate has been determined by: the compatibility gametophyte at genotypes studied, the coincidence in flowering donor and receiver corn, the isolation distance as well as the prevailing wind direction of pollination period. Under these circumstances, the coexistence of the genetically modified and conventional corn it is not possible, excepting the situation when we use isolation distances for over 40 m or other strategies. [ABSTRACT FROM AUTHOR]

Climate change is expected to negatively impact species worldwide, with varied ecological and evolutionary responses. Relatively sessile taxa, such as amphibians, will likely be precluded from large-scale migration in response to climate change, thus necessitating evolutionary and/or developmental responses "in place". Phenotypic plasticity may assist in mitigating climate change effects under such circumstances by allowing populations to "track" changing climate with appropriate phenotypic responses. However, geographically marginal populations may exhibit reduced capacities for phenotypic plasticity in response to climate change, though this relationship has not been directly tested. To determine how geographically central and marginal populations respond to climate change via phenotypic plasticity, we monitored the growth and development of larval Jefferson salamanders (Ambystoma jeffersonianum (Green 1827)) under current, and predicted future, climate scenarios using a mesocosm design. Although phenotypic plasticity occurred in both edge and core populations, there was no statistically significant difference in larval growth, survivorship, time to metamorphosis, or size at metamorphosis between core and edge populations under reduced hydroperiods. These results do not support assumptions of the abundant center distribution, which assumes populations in closer proximity to edges of species' geographic ranges exhibit reduced genetic diversity due to smaller population sizes than core populations, thereby limiting plastic responses in marginal populations. Our results could be explained by high habitat heterogeneity at range edges, which may prime peripheral populations for more varied responses. Future genetic studies may be beneficial in explaining possible differences between core and edge populations that may account for equivalent responses to climate change, such as gene flow between populations or genetic swamping. Factors such as these could subsequently impact the plastic responses of differing populations across species' geographic ranges. [ABSTRACT FROM AUTHOR]

I surveyed seedlings grown from seeds extracted from the cones of baldcypress (Taxodium distichum) and pondcypress (Taxodium ascendens) trees to determine the potential for cross-pollination. Two parent trees were sampled from populations that are less than 1.5 miles apart near Walterboro, SC. A PCR-RFLP analysis was conducted of a single nucleotide polymorphism in the trnC-ycf6 intergenic spacer region of the chloroplast that was identified by Lickey (unpubl.) as a putative diagnostic character separating baldcypress and pondcypress. The haplotypes of 175 seedlings originating from the two baldcypress parents and 92 seedlings originating from the two pondcypress parents were compared to the haplotypes of each parent. Preliminary data confirms that chloroplasts are inherited through the pollen in Taxodium, and that baldcypress haplotypes can be found in some pondcypress seedlings and vice versa. [ABSTRACT FROM AUTHOR]

The ability to accurately delimit species is of vital importance, particularly when dealing with taxa whose speciation is not immediately apparent. Phylogeographical analysis has emerged as a method that allows us to link micro and macroevolutionary processes in order to better understand speciation and divergence of sister taxa. Until recently, the Three-lined salamander (Eurycea guttolineata) was considered to be a subspecies of the Long-tailed Salamander (Eurycea longicauda). The most recent taxonomic analysis used both morphology and allozyme data to support the status of E. guttolineata as its own species. Our study aimed to produce a phylogenetic reconstruction of intraspecies variation across the range of E. guttolineata, with the intention of providing reliable data for future comparison studies of E. guttolineata and E. longicauda. Using mtDNA analyses of the cytochrome b (Cyt b) gene and Bayesian inference models, we produced a phylogenetic reconstruction of E. guttolineata. Additionally, we were able to compare cyt b haplotypes of E. guttolineata, and E. longicauda. Our analysis of E. guttolineata was characterized by a surprisingly low level of genetic diversity. This could potentially be due to a recent range expansion, or a large amount of gene flow between subpopulations throughout their range. Of utmost interest in our findings, was the identification of cyt b haplotypes characteristic of E. guttolineata in southern populations of E. longicauda (within the species contact zone). Further investigation of the species contact zone is needed, and hybridization frequencies in this zone may provide insights on determining parapatric speciation between these two species. [ABSTRACT FROM AUTHOR]

There are seven named taxa of the Trillium erectum L. species complex that are native to North America, many of which are experiencing secondary contact and hybridizing due to a lack of reproductive isolating mechanism. This project will focus on T. erectum var. album, a white flowered taxa, T. erectum var. erectum, a red flowered taxa, and T. rugelii, a white flowered taxa, each of which occurs in the southern Appalachian Mountains and are found in populations that overlap in geographic range and flowering phenology. Using three microsatellite loci developed for a related trillium species, this study examines hybridization and genetic structure of several populations of the T. erectum species complex, located in three counties in the western region of North Carolina, to determine if different taxa growing in mixed populations are interbreeding, and if so, quantify the amount of admixture and examine what factors, taxon identity, geographic range or flower color, are most influencing hybridization. Allele frequency analyses of microsatellite loci were used to compare the populations. We performed Principle Components Analysis comparing using pairwise comparisons of both fixation index and Nei's Genetic distance calculations for each geographic population. Structure analysis was used to identify populations and quantify admixture based on allele frequency and assumptions of gene flow using Bayesian statistical methods. Results from population genetics and Structure analyses suggest that allele sharing occurs primarily based on taxon identity and geographic proximity, but flower color may also play a role in influencing gene flow. [ABSTRACT FROM AUTHOR]

The Eastern Sub-Continental Divide separates bodies of water in Georgia, leading them east to the Atlantic Ocean, or west to the Gulf of Mexico. This study seeks to answer the question of if/how the continental divide affects gene flow within aquatic species. Since the continental divide separates rivers, our hypothesis is that it would also draw a barrier between fish populations. A paired samples design was used to sample fish from headwater streams in the Chattahoochee and Ocmulgee River watersheds. After collection, tissue samples were assessed via PCR (using mitochondrial and nuclear genes), sequencing, and phylogenetic analysis. The main fish species found in these streams belong to genera Semotilus, Nocomis, Notropis, and Campostoma; all in the family Cyprinidae. Initial results of select gene regions have given some support to the continental divide gene flow hypothesis. However, a mito-nuclear incongruence has been observed in the phylogenetic analyses. Mitochondrial phylogenetic patterns for Nocomis leptocephalus (Bluehead chub) suggest that gene flow within the Chattahoochee watershed may be more limited than between watersheds across the divide. [ABSTRACT FROM AUTHOR]