James H. Fullard, Hannah M. ter Hofstede, John M. Ratcliffe,
Gerald S. Pollack, Gian S. Brigidi, Robin M. Tinghitella & Marlene Zuk
(2010): Release from bats: genetic distance and sensoribehavioural
regression in the Pacific field cricket, Teleogryllus oceanicus.
Naturwissenschaften 97 (1), 53-61.
Abstract: The auditory thresholds of the AN2 interneuron and the behavioural
thresholds of the anti-bat flight-steering responses that this cell evokes
are less sensitive in female Pacific field crickets that live where bats
have never existed (Moorea) compared with individuals subjected to intense
levels of bat predation (Australia). In contrast, the sensitivity of the
auditory interneuron, ON1 which participates in the processing of both
social signals and bat calls, and the thresholds for flight orientation to a
model of the calling song of male crickets show few differences between the
two populations. Genetic analyses confirm that the two populations are
significantly distinct, and we conclude that the absence of bats has caused
partial regression in the nervous control of a defensive behaviour in this
insect. This study represents the first examination of natural evolutionary
regression in the neural basis of a behaviour along a selection gradient
within a single species.
URL: http://www.springerlink.com/content/2162832629557488/
For reprints please contact James H. Fullard (Email:
Chaminda P. Ratnayake, Eben Goodale & Sarath W. Kotagama (2010): Two
sympatric species of passerine birds imitate the same raptor calls in alarm
contexts. Naturwissenschaften 97 (1), 103-108.
Abstract: While some avian mimics appear to select sounds randomly, other
species preferentially imitate sounds such as predator calls that are
associated with danger. Previous work has shown that the Greater
Racket-tailed Drongo (Dicrurus paradiseus) incorporates predator calls and
heterospecific alarm calls into its own species-typical alarm vocalizations.
Here, we show that another passerine species, the Sri Lanka Magpie (Urocissa
ornata), which inhabits the same Sri Lankan rainforest, imitates three of
the same predator calls that drongos do. For two of these call types, there
is evidence that magpies also use them in alarm contexts. Our results
support the hypothesis that imitated predator calls can serve as signals of
alarm to multiple species.
URL: http://www.springerlink.com/content/d6347301447452h6/
For reprints please contact Chaminda P. Ratnayake (Email:
Volker B. Deecke, Lance G. Barrett-Lennard, Paul Spong & John K. B. Ford
(2010): The structure of stereotyped calls reflects kinship and social
affiliation in resident killer whales (Orcinus orca). Naturwissenschaften 97
(5), 513-518.
Abstract: A few species of mammals produce group-specific vocalisations that
are passed on by learning, but the function of learned vocal variation
remains poorly understood. Resident killer whales live in stable matrilineal
groups with repertoires of seven to 17 stereotyped call types. Some types
are shared among matrilines, but their structure typically shows
matriline-specific differences. Our objective was to analyse calls of nine
killer whale matrilines in British Columbia to test whether call similarity
primarily reflects social or genetic relationships. Recordings were made in
1985?1995 in the presence of focal matrilines that were either alone or with
groups with non-overlapping repertoires. We used neural network
discrimination performance to measure the similarity of call types produced
by different matrilines and determined matriline association rates from 757
encounters with one or more focal matrilines. Relatedness was measured by
comparing variation at 11 microsatellite loci for the oldest female in each
group. Call similarity was positively correlated with association rates for
two of the three call types analysed. Similarity of the N4 call type was
also correlated with matriarch relatedness. No relationship between
relatedness and association frequency was detected. These results show that
call structure reflects relatedness and social affiliation, but not because
related groups spend more time together. Instead, call structure appears to
play a role in kin recognition and shapes the association behaviour of
killer whale groups. Our results therefore support the hypothesis that
increasing social complexity plays a role in the evolution of learned
vocalisations in some mammalian species.
URL: http://www.springerlink.com/content/q12p250238136628/
For reprints please contact Volker B. Deecke (Email:
Kind regards
Sonja
**************************
Dr. Sonja Amoser
Steinrieglstraße 286
3400 Weidlingbach
Austria
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