scholarly journals Signal honesty and predation risk among a closely related group of aposematic species

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Lina María Arenas ◽  
Dominic Walter ◽  
Martin Stevens
2011 ◽  
Vol 7 (4) ◽  
pp. 493-495 ◽  
Author(s):  
Tonya M. Haff ◽  
Robert D. Magrath

Begging by nestling birds has been used to test evolutionary models of signalling but theory has outstripped evidence. Eavesdropping predators potentially impose a cost on begging that ensures signal honesty, yet little experimental evidence exists for such a cost at active nests because the use of artificial nests, long playback bouts and absence of parents may have exaggerated costs. We broadcast short periods (1 h) of either nestling vocalizations or background noise at active white-browed scrubwren, Sericornis frontalis , nests. Nestlings called naturally during both treatments, allowing us to test whether elevated calling increases risk, a key but rarely tested assumption of evolutionary models. Predators visited nests exclusively during periods of elevated calling. Furthermore, playbacks affected neither adult visits nor nestling activity, suggesting that calling alone attracted predators. Adults gave alarm calls and nestlings usually called less when predators approached nests. Predation risk to broods is, therefore, likely to fluctuate substantially over short periods of time, depending on nestling hunger and whether adults or young have detected predators. This study confirms a present-day cost of nestling begging, demonstrates that this cost can be incurred over short periods and supports the importance of parent–offspring antipredator strategies in reducing predation risk.


2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.


2012 ◽  
Vol 132 (2) ◽  
pp. 231-237
Author(s):  
Yuuki Imanara ◽  
Kota Itakura ◽  
Masaki Samejima ◽  
Masanori Akiyoshi

2016 ◽  
Vol 52 ◽  
pp. 82-94 ◽  
Author(s):  
A. Ye. Pochukalin

One of the ways of increasing level of animal economically useful traits is selection work with farm families. In pedigree cattle breeding of Ukraine families are a statistical component of breed genealogy. Among the main scientific works on working with families, it should be noted minimum number of female ancestors, proposed by D. T. Vinnichuk, to determine the breeding value, different categories, classification and techniques for evaluating related groups of females. The aim of our research was to analyse importance of farm families for genealogical structure of the breed. The research was on basis of data of primary breeding records at the herd of Volyn Beef cattle of “Zorya” breeding farm, Kovel district, Volyn region. Akula 102, Galka 37 and Galka 1537 families belonging to Krasavchyk 3004 bloodline, Smorodyna 613, Korona 2382 and Visla 1016 families – Tsebryk 3888 bloodline, Kalyna 212, Verba 1536 and Garna 536 families – Yamb 3066 bloodlines, Kazka 433, Galka 421 and Bystra 1124 families – Buinyi 3042 bloodline, Rozetka 1313, Arfa 599 and Bulana 943 families – Sonnyi-Kaktus 3307-9828 bloodline, and Palma 275, Desna 870 and Veselka 444 families – Mudryi 9100 bloodline were characterized. Belonging to a bloodline was determined by the father's side of female ancestors. Structural units of families: branches, branching with identifying the best individuals on breeding traits were submitted to identify the best combinations and successful use of closely related breeding. Comparing assessment of related groups of females on the main breeding traits belonging to Krasavchyk 3004 bloodline, it was noted that the cows of Akula 102 family predominated in live weight at 5 years’ age, milk ability and economic use duration, whereas the cows of Galka 1537 family – on traits of reproductive ability. Smorodyna 613 family of Tsebryk 3888 bloodline had high duration of economic use and cows’ live weight at 5 years’ age compared with Korana 2382 and Visla 1016 families with equal values of the exterior traits (height measures) and coefficient of reproductive ability. The families of Mudryi 9100 bloodline in terms of reproduction (calving interval, coefficient of reproductive ability) had the highest figures of cows’ milk ability and live weight. The cows of Bulana 943 family had a considerable predominance over representatives of Rozetka 1313 and Arfa 599 families of Sonnyi-Kaktus 3307-9828 bloodline by main economically useful traits. High indices of reproductive ability were noted in these families. Heifers of the families of Buinyi 3042 bloodline had high live weight at 18 months’ age at average values of milk ability and cows’ live weight at 5 years’ age. More equal figures of growth rate, exterior and economic use duration were observed in the cows of Kalyna 212, Verba 1536 and Garna 536 families of Yamb 3066 bloodline. Breeding by families in beef cattle breeding is an important element of selection, because it allows to evaluate not only related group of female ancestor, but also to analyse a successful combination with lines and purposeful use of closely related breeding by the best representatives of a breed.


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