scholarly journals Social selection parapatry in an Afrotropical sunbird

2015 ◽  
Author(s):  
Jay P McEntee ◽  
Joshua Penalba ◽  
Chacha Werema ◽  
Elia Mulungu ◽  
Maneno Mbilinyi ◽  
...  
Keyword(s):  
Contact Zone ◽  
Cultural Transmission ◽  
Song Learning ◽  
Social Selection ◽  
Future Studies ◽  
Trait Divergence ◽  
Song Divergence ◽  
Recent Species ◽  
Wide Contact ◽  
Range Overlap

The extent of range overlap of incipient and recent species depends on the type and magnitude of phenotypic divergence that separates them. Trait divergence by social selection likely initiates many speciation events, but may yield niche-conserved lineages predisposed to limit each others ranges via ecological competition. Here we examine this neglected aspect of social selection speciation theory in relation to the discovery of a non-ecotonal species border between sunbirds. We find that Nectarinia moreaui and N. fuelleborni meet in a ~6 km wide contact zone, as estimated by molecular cline analysis. These species exploit similar bioclimatic niches, but sing highly divergent learned songs, consistent with divergence by social selection. Cline analyses suggest that within-species stabilizing social selection on song-learning predispositions maintains species differences in song despite both hybridization and cultural transmission in the contact zone. We conclude that ecological competition between moreaui and fuelleborni contributes to the stabilization of the species border, but that ecological competition acts in conjunction with reproductive interference. The evolutionary maintenance of learned song differences in a hybrid zone recommend this study system for future studies on the mechanisms of learned song divergence and its role in speciation.

Homoplasy and extinction: the phylogeny of cassidulid echinoids (Echinodermata)

2019 ◽  
Vol 187 (3) ◽  
pp. 622-660 ◽  
Author(s):  
Camilla Souto ◽  
Rich Mooi ◽  
Luciana Martins ◽  
Carla Menegola ◽  
Charles R Marshall
Keyword(s):  
Evolutionary History ◽  
Cladistic Analysis ◽  
Future Studies ◽  
Novel Traits ◽  
The Family ◽  
Phylogenetic Resolution ◽  
History Of ◽  
Recent Species ◽  
Taxonomic Implications ◽  
High Diversity

Abstract Inclusion of fossils can be crucial to address evolutionary questions, because their unique morphology, often drastically modified in recent species, can improve phylogenetic resolution. We performed a cladistic analysis of 45 cassidulids with 98 characters, which resulted in 24 most parsimonious trees. The strict consensus recovers three major cassiduloid clades, and the monophyly of the family Cassidulidae is not supported. Ancillary analyses to determine the sensitivity of the phylogeny to missing data do not result in significantly different topologies. The taxonomic implications of these results, including the description of a new cassiduloid family and the evolution of some morphological features, are discussed. Cassiduloids (as defined here) most probably originated in the Early Cretaceous, and their evolutionary history has been dominated by high levels of homoplasy and a dearth of unique, novel traits. Despite their high diversity during the Palaeogene, there are only seven extant cassiduloid species, and three of these are relicts of lineages dating back to the Eocene. Future studies of the biology of these poorly known species, some of which brood their young, will yield further insights into the evolutionary history of this group.

scholarly journals Cultural transmission and its possible effect on urban acoustic adaptation of the great tit Parus major

2015 ◽  
Vol 38 (2) ◽  
pp. 221-231
Author(s):  
J. Bueno-Enciso ◽  
◽  
D. Núñez-Escribano ◽  
J. J. Sanz ◽  
◽  
...  
Keyword(s):  
Background Noise ◽  
Cultural Transmission ◽  
Parus Major ◽  
Great Tit ◽  
High Pitch ◽  
Cultural Wealth ◽  
Minimum Frequency ◽  
Song Divergence ◽  
Pause Length ◽  
Song Types

Urban great tits (Parus major) sing with a higher minimum frequency than their forest conspecifics. Cultural processes may account at least in part for the song divergence in city birds as great tits learn their repertoire from conspecifics and switch to high pitch song types in presence of background noise. However, in small cities, this process of cultural divergence could be constrained because it is likely that these birds have a greater exchange of song types with the outside. We tested this prediction by recording great tit songs in a small city (Toledo, central Spain) and in a nearby forest. We found that background noise and the peak and the maximum frequency of songs were higher in the city but the minimum frequency did not differ. The pause length was also longer in forest birds. Seventy percent of the song types were shared between Toledo and the nearby forest. These results suggest that the small size of Toledo allows a homogenized cultural wealth, preventing the development of a high pitch song as observed in larger cities.

scholarly journals Song hybridization events during revolutionary song change provide insights into cultural transmission in humpback whales

2017 ◽  
Vol 114 (30) ◽  
pp. 7822-7829 ◽  
Author(s):  
Ellen C. Garland ◽  
Luke Rendell ◽  
Luca Lamoni ◽  
M. Michael Poole ◽  
Michael J. Noad
Keyword(s):  
Cultural Transmission ◽  
Structural Similarity ◽  
Song Learning ◽  
Humpback Whales ◽  
Human Language ◽  
Structural Pattern ◽  
Language And Culture ◽  
South Pacific Ocean ◽  
Cultural Trait ◽  
Song Types

Cultural processes occur in a wide variety of animal taxa, from insects to cetaceans. The songs of humpback whales are one of the most striking examples of the transmission of a cultural trait and social learning in any nonhuman animal. To understand how songs are learned, we investigate rare cases of song hybridization, where parts of an existing song are spliced with a new one, likely before an individual totally adopts the new song. Song unit sequences were extracted from over 9,300 phrases recorded during two song revolutions across the South Pacific Ocean, allowing fine-scale analysis of composition and sequencing. In hybrid songs the current and new songs were spliced together in two specific ways: (i) singers placed a single hybrid phrase, in which content from both songs were combined, between the two song types when transitioning from one to the other, and/or (ii) singers spliced complete themes from the revolutionary song into the current song. Sequence analysis indicated that both processes were governed by structural similarity rules. Hybrid phrases or theme substitutions occurred at points in the songs where both songs contained “similar sounds arranged in a similar pattern.” Songs appear to be learned as segments (themes/phrase types), akin to birdsong and human language acquisition, and these can be combined in predictable ways if the underlying structural pattern is similar. These snapshots of song change provide insights into the mechanisms underlying song learning in humpback whales, and comparative perspectives on the evolution of human language and culture.

Catalog of Recent and fossil turrids (Mollusca: Gastropoda)

Zootaxa ◽  
2004 ◽  
Vol 682 (1) ◽  
pp. 1 ◽  
Author(s):  
JOHN K. TUCKER
Keyword(s):  
Preliminary Analysis ◽  
Sensu Stricto ◽  
Species Group ◽  
Species Level ◽  
Valid Species ◽  
Fossil Species ◽  
Future Studies ◽  
Secondary Literature ◽  
Recent Species ◽  
Geographic Regions

More than 11,350 species group taxa have at one time or another been assigned to the Conoidean gastropod group commonly referred to as turrids. A catalog including Recent and fossil species belonging to the Drilliidae, Pseudomelatomidae, Strictispiridae, Turridae, and six of the seven subfamilies of the Conidae is presented. Species described in the Terebridae and the Coninae (sensu stricto) are excluded. The catalog is descriptive and no new generic assignments are made nor are new synonymies proposed. However, much of the secondary literature is also reviewed for each taxon, allowing previously proposed synonymies and generic assignments to be quickly found and evaluated. Preliminary analysis of the taxa included found temporal and geographical variation in the make up of Conoidean faunas. In general, Conidae (sensu stricto) have increased in importance, whereas Turridae have declined in importance from Cretaceous to Recent. In all extant faunas, Conidae (sensu stricto) dominate and range from 44.8% to 91.5% of the faunas from broadly defined geographic regions. Species diversity is high with more than 3000 Recent taxa potentially valid species. With a 38 species/year rate of species description, the number of valid Recent species could increase by one-third in the next 50 years. Because slightly more than one-half of the taxa are fossil species and description of new species is rapid among the fossils, known diversity is also increasing among fossil taxa. Unfortunately a large number of species-level taxa were found that are little known and need study to determine their place in turrid systematics. Regardless, the catalog provides a foundation for future studies of these important marine carnivorous gastropods.

scholarly journals More Mountain Chickadees (Poecile gambeli) sing atypical songs in urban than in rural areas

2019 ◽  
Vol 133 (1) ◽  
pp. 28-33
Author(s):  
Stefanie E. LaZerte ◽  
Kristen L.D. Marini ◽  
Hans Slabbekoorn ◽  
Matthew W. Reudink ◽  
Ken A. Otter
Keyword(s):  
British Columbia ◽  
Population Density ◽  
Habitat Quality ◽  
Rural Areas ◽  
Song Learning ◽  
Novel Ecosystems ◽  
Urbanization Gradient ◽  
Future Studies ◽  
Poecile Gambeli ◽  
Mountain Chickadees

Urbanization results in novel ecosystems with unique challenges. These may lead to problems during song learning or development and could result in the singing of atypical songs. During studies of Mountain Chickadees (Poecile gambeli) and urbanization in British Columbia, Canada, we observed males singing atypical songs along an urbanization gradient. We found that eight of 78 males consistently sang atypical songs and the odds of singing atypical songs increased with urbanization. We explored several explanations including habitat quality, population density, and bioacoustics. Future studies investigating causes and consequences of atypical singing will clarify effects of urbanization on Mountain Chickadees.

scholarly journals Inferring punctuated evolution in the learned songs of African sunbirds

2019 ◽  
Author(s):  
Jay P. McEntee ◽  
Gleb Zhelezov ◽  
Chacha Werema ◽  
Nadje Najar ◽  
Joshua V. Peñalba ◽  
...  
Keyword(s):  
Animal Communication ◽  
Rapid Evolution ◽  
Song Learning ◽  
Frequent Change ◽  
Adaptive Landscapes ◽  
Song Divergence ◽  
Long Time ◽  
Long Timescales ◽  
Sky Island ◽  
Punctuated Evolution

AbstractSignals used in animal communication, especially those that are learned, are thought to be prone to rapid and/or regular evolution. It has been hypothesized that the evolution of song learning in birds has resulted in elevated diversification rates, as learned song may be subject to especially rapid evolution, and song is involved in mate choice. However, we know little about the evolutionary modes of learned song divergence over timescales relevant to speciation. Here we provide evidence that aspects of the territorial songs of Eastern Afromontane sky island sunbirds Cinnyris evolve in a punctuated fashion, with periods of stasis, on the order of hundreds of thousands of years or more, broken up by strong evolutionary pulses. Stasis in learned songs is inconsistent with learned traits being subject to constant or frequent change, as would be expected if selection does not constrain song phenotypes, or if novel phenotypes are frequently advantageous. Learned song may instead follow a process resembling peak shifts on adaptive landscapes. While much research has focused on the potential for rapid evolution in bird song, our results suggest that selection can tightly constrain the evolution of learned songs over fairly long timescales. More broadly, these results demonstrate that some aspects of highly variable, plastic traits can exhibit punctuated evolution, with stasis over fairly long time periods.

An Early Developmental Marker for Radial Glia in Rat Spinal Cord

1996 ◽  
Vol 54 ◽  
pp. 36-37
Author(s):  
V. Kriho ◽  
H.-Y. Yang ◽  
C.-M. Lue ◽  
N. Lieska ◽  
G. D. Pappas
Keyword(s):  
Spinal Cord ◽  
Intermediate Filament ◽  
Radial Glia ◽  
Rat Spinal Cord ◽  
Future Studies ◽  
Spinal Cord Development ◽  
Median Septum ◽  
Differentiation Marker ◽  
Early Developmental ◽  
Developing Rat

Radial glia have been classically defined as those early glial cells that radially span their thin processes from the ventricular to the pial surfaces in the developing central nervous system. These radial glia constitute a transient cell population, disappearing, for the most part, by the end of the period of neuronal migration. Traditionally, it has been difficult to definitively identify these cells because the principal criteria available were morphologic only.Using immunofluorescence microscopy, we have previously defined a phenotype for radial glia in rat spinal cord based upon the sequential expression of vimentin, glial fibrillary acidic protein and an intermediate filament-associated protein, IFAP-70/280kD. We report here the application of another intermediate filament-associated protein, IFAP-300kD, originally identified in BHK-21 cells, to the immunofluorescence study of radial glia in the developing rat spinal cord.Results showed that IFAP-300kD appeared very early in rat spinal cord development. In fact by embryonic day 13, IFAP-300kD immunoreactivity was already at its peak and was observed in most of the radial glia which span the spinal cord from the ventricular to the subpial surfaces (Fig. 1). Interestingly, from this time, IFAP-300kD immunoreactivity diminished rapidly in a dorsal to ventral manner, so that by embryonic day 16 it was detectable only in the maturing macroglial cells in the marginal zone of the spinal cord and the dorsal median septum (Fig. 2). By birth, the spinal cord was essentially immuno-negative for this IFAP. Thus, IFAP-300kD appears to be another differentiation marker available for future studies of gliogenesis, especially for the early stages of radial glia differentiation.

Autophagy and ageing: implications for age-related neurodegenerative diseases

2013 ◽  
Vol 55 ◽  
pp. 119-131 ◽  
Author(s):  
Bernadette Carroll ◽  
Graeme Hewitt ◽  
Viktor I. Korolchuk
Keyword(s):  
Neurodegenerative Diseases ◽  
Energy Availability ◽  
Future Studies ◽  
Intracellular Degradation ◽  
Age Related ◽  
Autophagy Induction ◽  
Social Importance ◽  
Cellular Dysfunction ◽  
Autophagy Activity ◽  
Intense Research

Autophagy is a process of lysosome-dependent intracellular degradation that participates in the liberation of resources including amino acids and energy to maintain homoeostasis. Autophagy is particularly important in stress conditions such as nutrient starvation and any perturbation in the ability of the cell to activate or regulate autophagy can lead to cellular dysfunction and disease. An area of intense research interest is the role and indeed the fate of autophagy during cellular and organismal ageing. Age-related disorders are associated with increased cellular stress and assault including DNA damage, reduced energy availability, protein aggregation and accumulation of damaged organelles. A reduction in autophagy activity has been observed in a number of ageing models and its up-regulation via pharmacological and genetic methods can alleviate age-related pathologies. In particular, autophagy induction can enhance clearance of toxic intracellular waste associated with neurodegenerative diseases and has been comprehensively demonstrated to improve lifespan in yeast, worms, flies, rodents and primates. The situation, however, has been complicated by the identification that autophagy up-regulation can also occur during ageing. Indeed, in certain situations, reduced autophagosome induction may actually provide benefits to ageing cells. Future studies will undoubtedly improve our understanding of exactly how the multiple signals that are integrated to control appropriate autophagy activity change during ageing, what affect this has on autophagy and to what extent autophagy contributes to age-associated pathologies. Identification of mechanisms that influence a healthy lifespan is of economic, medical and social importance in our ‘ageing’ world.

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