Abstracts (first author)

Invited Speaker 

Ecology, immunogenomics and pathogen resistance in wildlife populations

Author(s): Sommer S

Summary:

In order to protect functional biodiversity and ecosystem services we need healthy populations depending on healthy environments. Understanding the complex interactions that occur between human-induced environmental changes, pathogen pressure and transmission, the potential of host adaptive genetic diversity in host-pathogen co-evolutionary processes and disease resistance is a challenging task. It requires an interdisciplinary approach which should aim to integrate knowledge from evolutionary theory, behavioral ecology, conservation biology and conservation genomics. Next generation sequencing is revolutionizing conservation research and the new technologies are likely to replace traditional genotyping methods to a great extent in the near future. We are able to address questions in non-model organism whose answers seemed out of reach just a few years ago. In my talk, I will illustrate recent advances, challenges and pitfalls of current developments in evolutionary conservation. Specifically, I will address 1) The effects of behavioral strategies in shaping the adaptive potential and its fitness-relevance 2) The effects of human induced changes on pathogen pressure 3) The functional importance of adaptive variability of endangered species in host-pathogen co-evolutionary processes and pathogen resistance 4) The current challenges and pitfalls of next generation sequencing approaches in conservation genomics



Abstracts (coauthor)

Summary:

Studies of immune gene variation in the Major Histocompatibility Complex (MHC) provide a powerful tool to investigate patterns of adaptative genetic diversity shaped by natural selection. The use of MHC makers in population genetics has grown to a great extant in the past few years. However, studies with non-model species are still challenging due to the lack of a references and information of loci number. The lesser anteater is a medium sized mammal of the order Pilosa. The species is geographically widespread, found throughout South America in several types of habitats such as grasslands, savannas, forests and wetlands. Such flexibility on habitat use may lead to local adaptations reflected in the species’ MHC gene diversity, accounting for different parasite pressures in the environment. To understand the contribution of natural selection to Tamandua tetradactyla populations we described the diversity of the MHC Class II DRB exon 2 gene. At first, Single Strand Conformation Polymorphism (SSCP) was used to screen diversity in order to develop the optimal primer pair for sequential amplification (i.e., the one that catches most diversity and shows less null alleles). DRB exon 2 was amplified in ten gDNA samples from individuals trapped at different geographical locations using three primer sets. PCR products were run twice on SSCP gels and sequenced. A fragment of 198 base pairs (66 aminoacids) was obtained, and no indels were found. After choosing the best primer set, a total of 22 alleles were detected on the aminoacid level (TateDRB01 to TateDRB22), and 26 on the nucleotide level. Between four and eight alleles were found per individual (average of 4.7), indicating the presence of at least two DRB loci. Secondly, 50 samples derived from four different biomes of the species occurrence are currently analysed through Next Generation Sequencing (NGS) on a 454 Junior platform. This will allow the analyses of the genetic structure of MHC DRB gene in the species.

Summary:

A central premise in Conservation Genetics is that genetic erosion occurring in declining populations reduces adaptive potential and compromises viability. However, functional variation is seldom assessed in endangered populations. Here we use the Major Histocompatibility Complex class I and II-DRB loci (MHC) as functional model loci to study the impact of the decline on Iberian lynx genetic variation, a species for which previous genetic studies have shown a strong decline in the neutral variation and concomitant fitness reductions.

We genotyped the most variable exon of MHC I and II-DRB genes in 300 individuals from the two extant wild and the captive populations using a 454 platform and a new pipeline analysis. We used transcriptomic and genomic data for primer design and expression analysis. Captive individuals, having a well-established pedigree, allowed us to infer composite haplotypes and to analyse segregation. We found a total of 13 and 6 alleles probably corresponding to 7 and 3 loci for MHCI and MHCII, respectively. One allele shows signals of pseudogenization and not all other alleles were confirmed to be expressed. In the case of MHCII, most individuals in the smallest and less diverse Doñana population show a three-allele profile, consistent with homozygosity at all three loci. Additionally global diversity levels for MCH_I and II are low compared to other felid species.

Our results suggest that the immune response in remnant Iberian lynx populations may be compromised and that the severe reduction and fragmentation may have eroded not only the neutral, but also the functional genomic diversity, thus compromising the evolutionary adaptive potential of the species.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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