25th Annual Computational Neuroscience Meeting: CNS-2016

Abstracts of the 25th Annual Computational Neuroscience Meeting: CNS-2016 Seogwipo City, Jeju-do, South Korea. 2–7 July 201

Female responses to male coos in the collared dove Streptopelia decaocto

Birdsong is one of the main models in sexual selection studies. Most investigations focused on oscines in which male song and female preference learning occur. Yet, some non-oscines are well suited for such studies as well. In Columbidae song learning does not occur. However, like in oscines, song is involved in inter- and intra-sexual interactions. Surprisingly, experimental evidence of female song-based preferences are still largely lacking in this group. We conducted playback tests on wild-caught Streptopelia decaocto females. We tested for the sexual function of song by playing decaocto songs versus songs of an unrelated species. We then investigated female responses to trill. Although they do not produce this trait, males react more strongly to artificially trilled decaocto songs, i.e. to conspecific songs in which a trill from a S. roseogrisea song has been inserted, than to normal decaocto songs. We also tested female responses to S. roseogrisea songs. Females flew more often and with a shorter latency during decaocto songs than during wren songs, suggesting that species recognition occurred, but we found no evidence of preference for trilled decaocto songs. The low activity observed during the experiment might have obscured actual preferences. Nevertheless, females consistently reacted more to normal decaocto songs than to trilled decaocto or roseogrisea songs. This contrasts with the strong responses for trilled decaocto songs and the virtual lack of reaction to S. roseogrisea songs observed in males. Thus, female collared doves, as receivers, may have different characteristics from males and impose constraints on the evolution of song

A new phylogeny of swiftlets (Aves: Apodidae) based on cytochrome-b DNA

Due to a lack of distinctive morphological characters, swift taxonomy and phylogeny has always been an area of disagreement. To shed more light on this subject, we reconstructed swift(let) phylogeny based on 1143 bp of mitochondrial cytochrome-b DNA sequence. Although this is not the first attempt to reconstruct swift phylogeny using molecular data, our results show higher support for many of the branches due to our much longer sequences. However, placement of Hydrochous is still unexpected. Implementation of more conservative genetic regions and sampling of more taxa could solve this problem. Most importantly, the Collocaliini resolve as a monophyletic group. The internal structure of the group shows that non-echolocating Collocalia and echolocating Aerodramus form two distinct clades. This is in congruence with earlier classifications based on morphological characters, but in contrast with more recent classifications. (C) 2003 Elsevier Science (USA). All rights reserved

Selection on Phalanx Development in the Evolution of the Bird Wing

The frameshift hypothesis is a widely accepted model of bird wing evolution. This hypothesis postulates a shift in positional values, or molecular-developmental identity, that caused a change in digit phenotype. The hypothesis synthesized developmental and paleontological data on wing digit homology. The “most anterior digit” (MAD) hypothesis presents an alternative view based on changes in transcriptional regulation in the limb. The molecular evidence for both hypotheses is that the MAD expresses Hoxd13 but not Hoxd11 and Hoxd12. This digit I “signature” is thought to characterize all amniotes. Here, we studied Hoxd expression patterns in a phylogenetic sample of 18 amniotes. Instead of a conserved molecular signature in digit I, we find wide variation of Hoxd11, Hoxd12, and Hoxd13 expression in digit I. Patterns of apoptosis, and Sox9 expression, a marker of the phalanx-forming region, suggest that phalanges were lost from wing digit IV because of early arrest of the phalanx-forming region followed by cell death. Finally, we show that multiple amniote lineages lost phalanges with no frameshift. Our findings suggest that the bird wing evolved by targeted loss of phalanges under selection. Consistent with our view, some recent phylogenies based on dinosaur fossils eliminate the need to postulate a frameshift in the first place. We suggest that the phenotype of the Archaeopteryx lithographica wing is also consistent with phalanx loss. More broadly, our results support a gradualist model of evolution based on tinkering with developmental gene expression

Snake Venom Gland Organoids

Wnt dependency and Lgr5 expression define multiple mammalian epithelial stem cell types. Under defined growth factor conditions, such Adult Stem Cells (ASCs) grow as 3D organoids that recapitulate essential features of the pertinent epithelium. Here, we establish long-term expanding venom gland organoids from several snake species. The newly assembled transcriptome of the Cape coral snake reveals that organoids express high levels of toxin transcripts. Single cell RNA sequencing of both organoids and primary tissue identifies distinct venom-expressing cell types as well as proliferative cells expressing homologs of known mammalian stem cell markers. A hard-wired regional heterogeneity in the expression of individual venom components is maintained in organoid cultures. Harvested venom peptides reflect crude venom composition and display biological activity. This study extends organoid technology to reptilian tissues and describes an experimentally tractable model system representing the snake venom gland

The importance of environmental variables for submerged macrophyte community assemblage and coverage in shallow lakes: differences between northern and southern Europe

Much information is available on community composition and abundance of submerged macrophytes in North temperate lakes, including their response to variation in environmental variables. Less is known about macrophytes in other climate regions. We studied 98 shallow lakes distributed in three different European latitudinal regions. The lakes were selected along mutually independent gradients of macrophyte coverage and total phosphorus and were sampled monthly from May to October for water chemistry and physical variables. We tested for changes in the impact of selected environmental variables on the macrophyte assemblage, coverage and richness in the three regions. Coverage was measured along transects during July/August and June in the northern/central and southern European lakes, respectively. Correspondence Discriminant Analysis was used to detect for differences in macrophyte composition among different regions, and univariate regression trees were used to detect relationships between environmental variables and macrophyte coverage and richness. In the northern lakes, the coverage was mainly related to chlorophyll a followed by pH, and richness was related to Secchi depth and chlorophyll a. In the southern lakes, pH was the key environmental variable for both coverage and richness. North–south differences may be of relevance for determining management strategies related to global climate change