Reproductive success of Mariana Swiftlets (Aerodramus bartschi) on the Hawaiian island of O'ahu

Mariana Swiftlets (Aerodramus bartschi) are federally listed as endangered, with populations currently limited to just three islands in the Mariana Islands plus an introduced population on the Hawaiian island of O'ahu. Before efforts are made to reintroduce Mariana Swiftlets to other islands in the Mariana archipelago, additional information is needed concerning their breeding biology. Therefore, our objective was to examine the reproductive biology of Mariana Swiftlets over five annual cycles on the Hawaiian island of O'ahu. This introduced population used a human‐made tunnel for roosting and nesting, and was studied as a surrogate to negate interference with endangered populations in the Mariana Islands. Active nests (N = 478) were observed in every month of the year, with peak nesting activity between May and September. All clutches consisted of one egg. Mean duration of incubation and nestling periods were 23.9 d (range = 18–30 d, N = 233) and 55.0 d (range = 41–84 d, N = 228), respectively. Estimated nest success was 63%. Over half (52%) of nest failures were attributed to eggs found on the tunnel floor. Predation by rats (Rattus spp.) was also an important cause of nest failure and often resulted in the loss of most active nests. However, Mariana Swiftlets did re‐nest after these predation events. Our results suggest that rat predation of both nests and adults may limit growth of the Mariana Swiftlet population on O'ahu, and could also affect the chances for successful establishment of relocated populations in the Mariana Islands. Another limiting factor on O'ahu is that only one nesting site is apparently available on the island. Current goals for downlisting Mariana Swiftlets from endangered to threatened include establishing populations on Guam, Rota, Aguiguan, and Saipan. To meet these goals, the population of Mariana Swiftlets on O'ahu can be important for testing reintroduction techniques, learning more about the natural history of these swiftlets, and providing individuals for reintroduction efforts in the Mariana Islands.     

THE INFLUENCE OF LIGHT ADAPTATION ON SUBSEQUENT DARK ADAPTATION OF THE EYE

The course of dark adaptation of the human eye varies with the intensity used for the light adaptation which precedes it. Preadaptation to intensities below 200 photons is followed only by rod adaptation, while preadaptation to intensities above 4000 photons is followed first by cone adaptation and then by rod adaptation. With increasing intensities of preadaptation, cone dark adaptation remains essentially the same in form, but covers an increasing range of threshold intensities. At the highest preadaptation the range of the subsequent cone dark adaptation covers more than 3 log units. Rod dark adaptation appears in two types—a rapid and a delayed. The rapid rod dark adaptation is evident after preadaptations to low intensities corresponding to those usually associated with rod function. The delayed rod dark adaptation shows up only after preadaptation to intensities which are hundreds of times higher than those which produce the maximal function of the rods in flicker, intensity discrimination, and visual acuity. The delayed form remains essentially constant in shape following different intensities of preadaptation. However, its time of appearance increases with the preadaptation intensity; after the highest preadaptation, it appears only after 12 or 13 minutes in the dark. These two modes of rod dark adaptation are probably the expression of two methods of formation of visual purple in the rods after its bleaching by the preadaptation lights.     

Fighting the good cause: meaning,purpose, difference,and choice

Concepts of cause, choice, and information are closely related. A cause is a choice that can be held responsible. It is a difference that makes a difference. Information about past causes and their effects is a valuable commodity because it can be used to guide future choices. Information about criteria of choice is generated by choosing a subset from an ensemble for ‘reasons’ and has meaning for an interpreter when it is used to achieve an end. Natural selection evolves interpreters with ends. Surviving genes embody a textual record of past choices that had favorable outcomes. Consultation of these archives guides current choices. Purposive choice is well-informed difference making.     

Live fast,die young: the life cycle of the brooding feather star Aporometra wilsoni (Echinodermata: Crinoidea)

We present here the first documentation of the entire life cycle of a crinoid. A population of the diminutive feather star Aporometra wilsoni, which broods larvae, was sampled near Adelaide, in the Gulf St Vincent, South Australia, every fortnight between February 2004 and February 2005. Body size, sex, and reproductive status were recorded for 30–50 individuals collected on each occasion. The population showed a sex ratio of 1:1, with unequivocal male and female specimens found in 10 of 13 months. The average size (arm length) of individuals increased until June, when it stabilized and females began to brood larvae. Females were found brooding larvae until November, when adults began senescing. By January, the majority of the population consisted of small recruits. The entire life cycle of this small ovoviviparous crinoid occurs over a single year, a life cycle that is unique among echinoderms.     

Response to vocal music in Angelman syndrome contrasts with Prader-Willi syndrome

Parent-offspring conflict—conflict over resource distribution within families due to differences in genetic relatedness—is the biological foundation for many psychological phenomena. In genomic imprinting disorders, parent-specific genetic expression is altered, causing imbalances in behaviors influenced by parental investment. We use this natural experiment to test the theory that parent-offspring conflict contributed to the evolution of vocal music by moderating infant demands for parental attention. Individuals with Prader-Willi syndrome, a genomic imprinting disorder resulting from increased relative maternal genetic contribution, show enhanced relaxation responses to song, consistent with reduced demand for parental investment (Mehr, Kotler, Howard, Haig, & Krasnow, 2017, Psychological Science). We report the necessary complementary pattern here: individuals with Angelman syndrome, a genomic imprinting disorder resulting from increased relative paternal genetic contribution, demonstrate a relatively reduced relaxation response to song, suggesting increased demand for parental attention. These results support the extension of genetic conflict theories to psychological resources like parental attention.