Population structure of short‐finned pilot whales in the oceanic archipelago of Madeira based on photo‐identification and genetic analyses: implications for conservation

Abstract

1. Pilot whales Globicephala spp. are known to display a hierarchical social pattern, but longitudinal data to infer population structure of short-finned pilot whales Globicephala macrorhynchus are rare.2. Using data collected between 2003-2011 in the oceanic archipelago of Madeira, the grouping structure of short-finned pilot whales was studied using photo-identification methods and mtDNA sequences and microsatellite markers to test the hypotheses that (1) there is at least one pelagic and one or more island-associated communities, and (2) groups are made of related individuals, with a matrilineal social structure.3. Pilot whales demonstrated a large degree of variability in site fidelity, including residents (up to 14-year interval), regular visitors and transients. The social and temporal analyses revealed a well-differentiated society with long-lasting relationships (of years). The genetic analyses suggested that individuals of the three residency patterns may not be genetically isolated, and that small groups are made up of related individuals, suggesting some degree of social philopatry, while large groups are probably temporary associations of smaller groups.4. It is proposed that the pilot whales encountered in Madeira belong to a single population encompassing several clans, possibly three clans of island-associated whales and others of transients, each containing two to three matrilineal pods, each with a mean of 15 individuals (SD=9,. We suggest that the clans interact for mating purposes when they meet.5. For management decisions, it is considered that the island-associated whales should not be regarded as demographically independent populations, but instead as stable social entities to be included in governmental management plans and requiring periodic evaluation of their status. The high proportion of marked individuals and low rate of mark change encourages further research in this species.

Site fidelity and movement patterns of short‐finned pilot whales within the Canary Islands: Evidence for resident and transient populations

“…Residency patterns in the archipelago were characterized by a mixture of 'residents', 'transients', and 'occasional' temporary migrants, in agreement with findings for other SFPW populations around oceanic islands (Alves et al, 2013;Mahaffy et al, 2015). Residency patterns in the archipelago were characterized by a mixture of 'residents', 'transients', and 'occasional' temporary migrants, in agreement with findings for other SFPW populations around oceanic islands (Alves et al, 2013;Mahaffy et al, 2015).…”

“…Animals sighted only once could be 'transients' passing through the archipelago, have ranges that barely overlap the study area, be behaviourally less likely to be captured, have died or permanently emigrated, or simply not have been resighted during the study period in the area (Alves et al, 2013). Animals sighted only once could be 'transients' passing through the archipelago, have ranges that barely overlap the study area, be behaviourally less likely to be captured, have died or permanently emigrated, or simply not have been resighted during the study period in the area (Alves et al, 2013).…”

“…Indeed, the individuals recaptured between Madeira and the Canary Islands 590.3 km apart (Servidio, 2014) appear not to be isolated events (Alves et al, 2019) The factors that influence residency patterns of pilot whales and their movements among the islands and archipelagos are poorly understood. Abend & Smith, 1999;Alves et al, 2013;. Abend & Smith, 1999;Alves et al, 2013;.…”

Long-Distance Travellers: Phylogeography of a Generalist Parasite, Pholeter gastrophilus, from Cetaceans

“…The ability of pelagic cetaceans to move over long distances has been documented for several species that serve as hosts for P . gastrophilus , including, e.g., the short-beaked common dolphin [8, 102], the oceanic populations of the bottlenose dolphin [103, 104], the dusky dolphin [105], the short-finned pilot whale [106, 107], and the sperm whale [108] (Table 1). However, we detected significant population structure in the Atlantic population of P .…”

Population Structure and Dynamics

“…molecular techniques (see below) to explore population structure. For example, Alves et al (2013) combined mitochondrial DNA (mtDNA) and microsatellite genetics with close to a decade of photo-id work to explore connectivity in island-associated and pelagic groups of pilot whales (Globicephala spp.) around Madeira.…”