Abstract Detail

Population Genetics

Arlinghaus, Kellen R [1], Mardonovich, Sandra [2], Moore, Richard C. [3].

Gene flow in wild populations of Carica papaya in the fragmented landscape of Central America.

Wild crop relatives serve as a natural genetic reservoir for crop improvement as they may harbor alleles that aid in disease resistance and environmental adaptability. Conservation of these wild relatives is essential for maintaining a robust gene pool for crop breeding efforts. One major threat to the reservoir of genetic diversity in wild populations is habitat fragmentation which isolates populations and reduces genetic admixture across agricultural lands. Carica papaya is a dioecious early successional species native to Central America that can be found growing along roadsides, abandoned fields, and secondary lowland forests. I hypothesize that the variable fragmented landscape in Central America isolates wild papaya populations, impeding gene flow and increasing inbreeding within populations. Populations of wild papaya were collected from both Costa Rica and Nicaragua including 8 regional populations in Costa Rica and 9 regional populations in Nicaragua. Levels and patterns of genetic differentiation were assessed using 20 microsatellite loci across the papaya genome. Gene flow was measured using pairwise F statistics, AMOVA, and STRUCTURE analysis and compared with cultivars. Distinct genetic clusters identified distinguished Costa Rican and Nicaraguan populations, with a zone of introgression identified in populations at the boundary between the two countries. Some introgression from cultivars was also observed in northwest Costa Rica. Connectivity throughout the landscape was further quantified using CIRCUITSCAPE toolbox in ArcGIS which uses circuit theory as an analog for gene flow throughout a heterogeneous landscape. Corridors of continuous forest were identified as potential areas for pollinators or seed dispersers to travel through while areas of heavy use like roads or farms added resistance to gene flow. If diversity is partitioned equally among populations, the loss of isolated populations can be tolerated without affecting the pool of allelic diversity. Alternatively, if populations are highly differentiated, extinction of local populations will result in permanent loss of population-specific genetic variation and conservation efforts should focus on preserving these populations for future use in crop improvement.

1 - Miami University, Botany, 700 East High St. , 333F PSN, OXford, Ohio, 45056, USA
2 - Miami University, Botany, 649 Erin Dr. Apt. #5, Oxford, OH, 45056, USA
3 - Miami University, Botany, 316 Pearson, Oxford, OH, 45056, USA

Keywords:
population genetics
gene flow.

Presentation Type: Oral Paper
Session: 39, Population Genetics
Location: 201/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 10:45 AM
Number: 39011
Abstract ID:691
Candidate for Awards:None