Passive and active parental food allocation in a songbird.

Parent-offspring conflict over food allocation can be modeled using two theoretical frameworks: passive (scramble competition) and active choice (signaling) resolution models. However, differentiating between these models empirically can be challenging. One possibility involves investigating details of decision-making by feeding parents. Different nestling traits, related to competitive prowess or signaling cryptic condition, may interact additively or non-additively as predictors of parental feeding responses. To explore this, we experimentally created even-sized, small broods of pied flycatchers and manipulated nestling cryptic quality, independently of size, by vitamin E supplementation. We explored how interactions between nestling cryptic condition, size, signals, and spatial location predicted food allocation and prey-testing by parents. Parents created the potential for spatial scramble competition between nestlings by feeding from and to a narrow range of nest locations. Heavier supplemented nestlings grew faster and were more likely to access profitable nest locations. However, the most profitable locations were not more contested, and nestling turnover did not vary in relation to spatial predictability or food supply. Postural begging was only predicted by nestling hunger and body mass, but parents did not favor heavier nestlings. This suggests that size-mediated and spatial competition in experimental broods was mild. Pied flycatcher fathers allocated food in response to nestling position and begging order, while mothers seemingly followed an active choice mechanism involving assessment of more complex traits, including postural intensity interacting with order, position, and treatment, and perhaps other stimuli when performing prey-testings. Differences in time constraints may underlie sex differences in food allocation rules.

Molecular characterization of haemosporidian and haemogregarine diversity in southwestern Iberian amphibians and reptiles.

The knowledge of the diversity and geographic distribution of parasite species is the first step towards understanding processes of global epidemiology and species conservation. Despite recent increases in research on haemosporidian and haemogregarine parasites of reptiles and amphibians, we still know little about their diversity and parasite-host interactions, especially in the Iberian Peninsula, where a few studies have been conducted. In this study, the haemosporidian and haemogregarine diversity and phylogenetic relationships of the parasites in southwestern Iberian amphibians and reptiles were assessed using PCR approaches on blood samples of 145 individuals from five amphibian and 13 reptile species. The amphibians did not present any of both groups of parasites studied. Regarding reptiles, five Hepatozoon, one Haemogregarina, and one Haemocystidum haplotypes were found infecting four different species, revealing new host records for these parasites. Among them, we found one new Haemocystidium haplotype and three new and a previously reported Hepatozoon haplotype from a north African snake. The latter finding suggests that some Hepatozoon parasites may not be host-specific and have large geographic ranges even crossing geographical barriers. These results increased the knowledge about the geographic distribution and the number of known host species of some reptile apicomplexan parasites, highlighting the great unexplored diversity of them in this region.