Rockhopper penguins are delimited as 2 species, the northern rockhopper (Eudyptes moseleyi) and the southern rockhopper (Eudyptes chrysocome), with the latter comprising 2 subspecies, the western rockhopper (Eudyptes chrysocome chrysocome) and the eastern rockhopper (Eudyptes chrysocome filholi). We conducted a phylogeographic study using multilocus data from 114 individuals sampled across 12 colonies from the entire range of the northern/southern rockhopper complex to assess potential population structure, gene flow, and species limits. Bayesian and likelihood methods with nuclear and mitochondrial DNA, including model testing and heuristic approaches, support E. moseleyi and E. chrysocome as distinct species lineages with a divergence time of 0.97 Ma. However, these analyses also indicated the presence of gene flow between these species. Among southern rockhopper subspecies, we found evidence of significant gene flow and heuristic approaches to species delimitation based on the genealogical diversity index failed to delimit them as species. The best-supported population models for the southern rockhoppers were those where E. c. chrysocome and E. c. filholi were combined into a single lineage or 2 lineages with bidirectional gene flow. Additionally, we found that E. c. filholi has the highest effective population size while E. c. chrysocome showed similar effective population size to that of the endangered E. moseleyi. We suggest that the current taxonomic definitions within rockhopper penguins be upheld and that E. chrysocome populations, all found south of the subtropical front, should be treated as a single taxon with distinct management units for E. c. chrysocome and E. c. filholi.
The foraging range during the breeding season and Austral winter period of Southern Rockhopper Penguins, Eudyptes c. chrysocome, has been previously documented within colonies along the coast of Argentina and in the Falkland (Malvinas) Islands. We examined annual movement patterns of Southern Rockhopper Penguins to better understand the utilization of their environment in southern Chile. 25 Southern Rockhopper Penguins from Isla Noir were equipped with global location sensors that logged light-levels, water immersion (wet/dry) and sea-surface temperatures (SST) providing daily position, water immersion, and environmental conditions. Five of the penguins were relocated on Isla Noir for data retrieval. Position data were converted into maps of kernel density estimates overlaid with average SST. Study penguins had greatest densities near the colony during the breeding season and dispersed to areas ranging from near the Falkland Islands to areas between 46°S to 57°S and 114°W to 97°W. The penguins utilized areas over the continental shelf during the breeding season and ranged to areas over the ocean basin during the Austral winter period, post-breeding season and molt. Coastal areas along the outer islands were used during the transitional periods between the breeding season and winter period. These data are important in defining the conservation management of the Southern Rockhopper Penguin in relation to fisheries-associated mortality and depletion of food sources.
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