Peter A. Ritchie

Mutation and Evolutionary Rates in Adélie Penguins from the Antarctic

Precise estimations of molecular rates are fundamental to our understanding of the processes of evolution. In principle, mutation and evolutionary rates for neutral regions of the same species are expected to be equal. However, a number of recent studies have shown that mutation rates estimated from pedigree material are much faster than evolutionary rates measured over longer time periods. To resolve this apparent contradiction, we have examined the hypervariable region (HVR I) of the mitochondrial genome using families of Adélie penguins (Pygoscelis adeliae) from the Antarctic. We sequenced 344 bps of the HVR I from penguins comprising 508 families with 915 chicks, together with both their parents. All of the 62 germline heteroplasmies that we detected in mothers were also detected in their offspring, consistent with maternal inheritance. These data give an estimated mutation rate (μ) of 0.55 mutations/site/Myrs (HPD 95% confidence interval of 0.29–0.88 mutations/site/Myrs) after accounting for the persistence of these heteroplasmies and the sensitivity of current detection methods. In comparison, the rate of evolution (k) of the same HVR I region, determined using DNA sequences from 162 known age sub-fossil bones spanning a 37,000-year period, was 0.86 substitutions/site/Myrs (HPD 95% confidence interval of 0.53 and 1.17). Importantly, the latter rate is not statistically different from our estimate of the mutation rate. These results are in contrast to the view that molecular rates are time dependent.

Gene flow on the ice: genetic differentiation among Adélie penguin colonies around Antarctica.

Each summer Adélie penguins breed in large disjunct colonies on ice‐free areas around the Antarctic continent. Comprising > 10 million birds, this species represents a dominant feature of the Antarctic ecosystem. The patchy distribution within a large geographical range, natal philopatry and a probable history of refugia, suggest that this species is likely to exhibit significant genetic differentiation within and among colonies. We present data from seven microsatellite DNA loci for 442 individuals from 13 locations around the Antarctic continent. With the exception of one locus, there was no significant genic or genotypic heterogeneity across populations. Pairwise FST values were low with no value > 0.02. When all colonies were compared in a single analysis, the overall FST value was 0.0007. Moreover, assignment tests were relatively ineffective at correctly placing individuals into their respective collection sites. These data reveal a lack of genetic differentiation between Adélie penguin colonies around the Antarctic continent, despite substantial levels of genetic variation. We consider this homogeneity in terms of the dispersal of individuals among colonies and the size of breeding groups and discuss our results in terms of the glacial history of Antarctica.

First records of egg masses of Nototodarus gouldi McCoy, 1888 (Mollusca: Cephalopoda: Ommastrephidae), with comments on egg‐mass susceptibility to damage by fisheries trawl

Abstract The egg mass and embryos of the ommastrephid squid Nototodarus gouldi McCoy, 1888 are reported for the first time, their identity confirmed by mitochondrial 16S rDNA sequence determination. The egg mass is a free‐floating gelatinous sphere of at least 1.5 m diameter and contains an estimated several thousand randomly distributed eggs; similar egg masses recorded from north‐eastern New Zealand waters of 1.0–2.0 m diameter are reported. Observed fluctuations in populations for this and other squid species may be a partial result of trawl damage to the egg masses.

New DNA markers for penguins

Penguins (Spheniscidae) represent a monophyletic group comprised of 17 species (Stonehouse 1975; Williams 1995). Found exclusively in the Southern Hemisphere, these flightless diving birds occupy a wide range of habitats from Antarctica to the Galapagos Islands (Williams 1995). Currently, ten species are listed on IUCN’s Red List (BirdLife International 2000) as either ‘endangered’ or ‘vulnerable’. Genetic markers would be useful for resolving issues relevant to the conservation of this group. The entire Adelie penguin mitochondrial (mt) DNA control region has been reported (Ritchie and Lambert 2000) but to date, no general spheniscid PCR-primers that target this useful hypervariable sequence exist. Here we report four novel polymerase chain reaction (PCR) primers designed for the mtDNA control region that amplify across a broad range of penguin species. In addition, we show cross-amplification of nuclear microsatellite loci isolated from Adelie penguins in other penguin species.

Identification of galaxiid nests, emigrating larvae and whitebait, using mitochondrial DNA control region sequences

Abstract We used mitochondrial (mt) DNA sequences to identify nests, emigrating larvae, and whitebait of three species of diadromous galaxiids, collected from eight locations in Taranaki and Manawatu, New Zealand. DNA was extracted from whole larvae and fin clips, and a 416 base pair (bp) sequence of mtDNA control region was determined. Four Galaxias fasciatus Gray (banded kokopu) and 12 G. postvectis Clarke (shortjaw kokopu) nests were identified. Galaxias postvectis, G. fasciatus, and G. brevipinnis Günther (koaro) individuals were detected migrating downstream from drift samples collected between May and June 2001. Furthermore, we identified three species from samples of whitebait revealing three G. postvectis, six G. fasciatus, and three G. brevipinnis. Species of larval eggs, larvae, and whitebait can be accurately identified by molecular methods. These methods provide an opportunity to help in the understanding of nest habitat choice, hatching time, migration, and choice of rivers by whitebait species.