Correlated evolution of nest and egg characteristics in birds

Correlational selection is defined as selection for adaptive character combinations, and it therefore favours combinations of coevolved traits via phenotypic integration. Whereas the evolution of avian nest-building and egg-laying characteristics are well understood, their correlated dynamics remain overlooked. Here, we examined patterns of correlated evolution between nest, egg and clutch characteristics in 855 species of birds from 90 families, representing nearly 9% and 33% of avian species- and family-level diversity. We show that the ancestral state of birds’ nests was semi-open with nest sites having since become progressively more open over time. Furthermore, nest characteristics appear to have influenced egg-laying patterns in that while semi-open nests with variable clutch sizes were probably ancestral, clutch sizes have declined over evolutionary time in both open and closed nests. Ancestrally, avian eggs were also large, heavy and either elliptic or round, and there have been high transition rates from elliptic to round eggs in open nests and vice versa in closed nests. Ancestrally, both unpigmented (white) and pigmented (blue–brown) eggs were laid in open nests, although blue–brown eggs have transitioned more to white over time in open and closed nests, independently. We conclude that there has been a remarkable level of correlated evolution between the nest and egg characteristics of birds, which supports scenarios of correlational selection on both of these extended avian phenotypes

Volumetric Changes of Mud on Mars: Evidence from Laboratory Simulations

International audienc

Accelerated avian invasion into the Mediterranean region endangers biodiversity and mandates international collaboration

Policy DirectionDespite posing a serious threat to global biodiversity, national and international management efforts have not been able to limit the spread of most invasive species. In highly dispersive species, local invasions may be followed by regional range expansion that crosses international borders. In such cases, independent management efforts of the invading population may be futile unless international collaboration is practiced. 2. We focus on the ongoing human-mediated invasion of the common myna Acridotheres tristis into the Mediterranean basin, a region rich in overall numbers of species and endemic species, where common mynas have been introduced into a handful of countries. Some introductions were followed by subsequent range expansions into neighbouring countries. This species poses major threats to the biodiversity of the Mediterranean which is already susceptible to biodiversity loss as the result of ongoing land use and climate changes. Without action, this species and possibly others similar to it, could have severe consequences for native ecosystems. 3. Policy implications. Given the regional scope of its invasion in the Mediterranean basin, common myna management requires an international collaboration to successfully prevent additional introductions and range expansions and to avoid accelerating threats to Mediterranean biodiversity, already at risk as a result of ongoing changes in land use and climate. We argue that international reciprocal transfer of information and the development of regional mitigation are essential for the successful management of the invasion of the common myna and other species into the Mediterraneaninfo:eu-repo/semantics/publishedVersio

The presence of ultrasonic harmonics in the calls of the rifleman (Acanthisitta chloris)

Ultrasonic vocalisations (frequencies > 20 kHz) have been extensively studied in the context of echolocation by bats and other mammals (Sales & Pye 1974; Wilson & Hare 2004). Ultrasonic calls have also been recorded from birds, including the blue-throated hummingbird ( Lampornis clemenciae ) (Pytte et al. 2004), where it was first thought that individuals made use of high pitch calls to avoid masking by background noise in a visually obscured environment. Similarly, city-dwelling great tits ( Parus major ) use song with a higher minimum frequency (although not ultrasonic) compared to woodland birds to communicate with conspecifics to avoid the predominantly low-frequency background noise in the city (Slabbekorn & Peet 2003). The theory that birds use ultrasound to avoid noise masking was discarded when it was discovered that there was no corresponding auditory brainstem response (i.e. sensory perception) to the ultrasonic calls in the hummingbirds producing those calls

Central place foraging by breeding Cook's petrel Pterodroma cookii: foraging duration reflects range, diet and chick meal mass

Pelagic seabirds are central place foragers during breeding and variation in foraging trip duration and range reflect differences in diet and chick provisioning, through the exploitation of divergent habitats of varying productivity. We tested whether these relationships hold in small procellarriids by equipping chick-rearing Cook's petrel Pterodroma cookii (200 g) with geolocation-immersion loggers, conducting isotope analysis of blood and measuring chick meal mass following foraging trips of varying duration. Cook's petrel tracked during chick rearing from Little Barrier Island (LBI) and Codfish Island (CDF), New Zealand had larger maximum ranges during longer foraging trips. Blood nitrogen isotope signatures (delta(15)N) of adults were significantly higher after foraging trips of longer duration, but not of greater maximum range. There was no significant relationship between blood carbon isotope signatures (delta(13)C) and foraging trip characteristics. Proportion of time spent on the sea surface and the mass of the meal brought back to chicks were consistently greater for Cook's petrel with larger maximum ranges, which in the case of birds from CDF coincided with productive subtropical convergence zone habitats. As predicted, trip duration reflected divergent foraging behaviours in Cook's petrel during breeding. We suggest that the availability of different prey is a key factor governing at-sea distributions and dietary composition of this species