Reduction of Paraoxonase Expression Followed by Inactivation across Independent Semiaquatic Mammals Suggests Stepwise Path to Pseudogenization.

Convergent adaptation to the same environment by multiple lineages frequently involves rapid evolutionary change at the same genes, implicating these genes as important for environmental adaptation. Such adaptive molecular changes may yield either change or loss of protein function; loss of function can eliminate newly deleterious proteins or reduce energy necessary for protein production. We previously found a striking case of recurrent pseudogenization of the Paraoxonase 1 (Pon1) gene among aquatic mammal lineages-Pon1 became a pseudogene with genetic lesions, such as stop codons and frameshifts, at least four times independently in aquatic and semiaquatic mammals. Here, we assess the landscape and pace of pseudogenization by studying Pon1 sequences, expression levels, and enzymatic activity across four aquatic and semiaquatic mammal lineages: pinnipeds, cetaceans, otters, and beavers. We observe in beavers and pinnipeds an unexpected reduction in expression of Pon3, a paralog with similar expression patterns but different substrate preferences. Ultimately, in all lineages with aquatic/semiaquatic members, we find that preceding any coding-level pseudogenization events in Pon1, there is a drastic decrease in expression, followed by relaxed selection, thus allowing accumulation of disrupting mutations. The recurrent loss of Pon1 function in aquatic/semiaquatic lineages is consistent with a benefit to Pon1 functional loss in aquatic environments. Accordingly, we examine diving and dietary traits across pinniped species as potential driving forces of Pon1 functional loss. We find that loss is best associated with diving activity and likely results from changes in selective pressures associated with hypoxia and hypoxia-induced inflammation.

Artificial insemination and parthenogenesis in the whitespotted bamboo shark Chiloscyllium plagiosum.

Non-lethal methods for semen collection from elasmobranchs to better understand species reproduction has accompanied the development of artificial insemination. Ejaculates (n = 82) collected from whitespotted bamboo sharks Chiloscyllium plagiosum (n = 19) were assessed and cold-stored raw or extended at 4 °C. Females (n = 20) were inseminated with fresh or 24-48 h cold-stored raw or extended semen and paternity of offspring determined with microsatellite markers. Insemination of females with fresh semen (n = 10) resulted in 80 hatchlings and 27.6% fertility. Insemination of females with semen cold-stored 24 h (n = 4) and 48 h (n = 1) semen resulted in 17 hatchlings and fertilization rates of 28.1% and 7.1% respectively. Two females inseminated with fresh or cold-stored semen laid eggs that hatched from fertilization and parthenogenesis within the same clutch. Parthenogenesis rate for inseminated females was 0.71%. Results demonstrate artificial insemination with cold-stored semen can provide a strategy for transport of male genetics nationally and internationally, precluding the need to transport sharks. Production of parthenotes in the same clutch as sexually fertilized eggs highlights the prevalence of parthenogenesis in whitespotted bamboo sharks and poses important considerations for population management.

Prognostic indicators for survival in African penguin chicks (Spheniscus demersus): A retrospective analysis.

Mystic Aquarium has successfully maintained an active breeding population of African penguins since 1990. Between 1990 and 2015, 477 eggs were laid, 84 of which were recommended for rearing according to the SSP Breeding and Transfer Plan. Sixty-five percent hatched successfully, and total fertility ranged from 56% to 78%. Of the 55 hatchlings, 60% of chicks reached fledgling age (80 days). Of the 22 chicks that died before fledging, 59% died within 7 days of hatching, and 82% within 30 days of hatching. Categories of mortality were broken down into the following categories: failure to thrive (in the absence of a definitive cause of death) (41%), respiratory disease (32%), parent-associated trauma (13%), congenital defects (9%), and gastrointestinal disease (5%). Analysis of associated factors identified a significant correlation between the hatch weights of chicks that survived beyond day 7 (60.5-66.0 g), and those that did not (49.5-59.5 g). Further positive correlations were established between chick hatch weight and both dam body weight, and egg weight. While hand-reared chicks gained weight more slowly than their parent-reared counterparts, results showed that rearing method had no significant impact on survival. The findings of this study provide a baseline for assessing reproductive success and chick mortality, and supply prognostic indicators for evaluating chick success in managed African penguin populations.