Fruit colour conceals endocarp dimorphism from avian seed dispersers in a tropical beach plant, Scaevola taccada (Goodeniaceae), found in Okinawa

2015 ◽  
Vol 31 (4) ◽  
pp. 335-344 ◽  
Author(s):  
Keita D. Tanaka ◽  
Tetsuo Denda ◽  
Keisuke Ueda ◽  
Naoko Emura
Keyword(s):  
Ocean Current ◽  
Fruit Colour ◽  
Honest Signalling ◽  
Apparent Lack ◽  
Congruence Principle ◽  
Modelling Studies ◽  
In The Wild ◽  
The Common ◽  
Seed Dispersers ◽  
Evolutionarily Stable

Abstract:Theory predicts that honest signalling strategies will not always be evolutionarily stable in interspecific communication, yet to demonstrate such a transition of signalling modality between honesty and dishonesty in the wild would be difficult. An endocarp dimorphism has been found in Scaevola taccada fruits: a morph with a cork substrate that facilitates ocean current seed dispersal and a morph without the cork. Both types of fruit are covered with sugar-containing flesh, and are similar in size and colour to one another (at least from a human perspective). The apparent lack of external differences between morphotypes could potentially degrade mutualistic relations between the plant and seed-dispersing birds because the presence of a cork could lower the fruit's nutritional value. Thus, unless seed dispersers can discriminate between the different types of fruit, this system may provide an example of a transition between honest and dishonest signalling. We examined S. taccada fruit and leaf colours from an avian visual perspective. Even though the fruits and leaves were different in colour from one another to birds, there was no perceivable difference in the colours between fruit morphotypes. Therefore, fruit colour is not an honest indicator of reward to seed dispersers. Further, we propose an adoption of a statistical method in avian visual modelling studies that avoids the common statistical errors, such as violation of the congruence principle.

scholarly journals Brief Mating Behavior at Dawn and Dusk and Long Nocturnal Matings in the Butterfly Melanitis leda

2020 ◽  
Vol 33 (2-4) ◽  
pp. 138-147
Author(s):  
Freerk Molleman ◽  
Sridhar Halali ◽  
Ullasa Kodandaramaiah
Keyword(s):  
Mating System ◽  
Mating Behavior ◽  
South India ◽  
Territorial Defense ◽  
Warm Up ◽  
Male Territoriality ◽  
In Captivity ◽  
In The Wild ◽  
The Common ◽  
Insight Into

Abstract Information on the mating system of an insect species is necessary to gain insight into sexual selection and population structure. Male territoriality of the common evening brown butterfly Melanitis leda has been studied in the wild, but other aspects of its mating system remain largely unknown. For a population of M. leda in South India, we observed male-male and male-female interactions in captivity, measured mating duration and spermatophore mass, and also determined the degree of polyandry in the wild. We found that mating behavior takes place for short periods of time around dawn and dusk. Our observations corroborate that males compete in aerial combats (twirling) and interfere with mating pairs. In the morning, they may use shivering to warm up. Females can twirl with males and refuse mating by pointing their abdomens upwards or by flying away. Males court females by fluttering their wings while perched behind females, and then initiate copulation by curling their abdomens ca. 180 degrees sideways to make genital contact. While in the morning, matings lasted on average one hour and twenty-three minutes and never exceeded three hours, in the evening, matings could be of similar duration, but 42% of butterflies only separated when dawn was approaching. However, such long nocturnal matings did not result in heavier spermatophores. The first spermatophore of a male tended to be larger than subsequent spermatophores. Together with previous studies on this species, our findings suggest that males compete mainly through territorial defense (as reported before), courtship performance, and interference, and to a lesser extent by providing spermatophores, while females exert some control over the mating system by the timing of their receptivity and mate choice.

Effect of ingestion by two frugivorous bat species on the seed germination of Ficus racemosa and F. hispida (Moraceae)

2007 ◽  
Vol 23 (1) ◽  
pp. 125-127 ◽  
Author(s):  
Zhan-Hui Tang ◽  
Aeshita Mukherjee ◽  
Lian-Xi Sheng ◽  
Min Cao ◽  
Bing Liang ◽  
...  
Keyword(s):  
Seed Germination ◽  
Digestive Tract ◽  
Plant Species ◽  
Transit Times ◽  
In The Wild ◽  
Ficus Racemosa ◽  
Seed Dispersers

Frugivorous bats are important seed dispersers for many plant species (Cox et al. 1991, Fleming & Heithaus 1981, Hodgkison et al. 2003a, McConkey & Drake 2006, Nyhagen et al. 2005, Utzurrum 1995). They regularly consume figs in the wild (Fujita & Tuttle 1991, Kalko et al. 1996, Shilton et al. 1999). Various species of pteropodid bats have been reported foraging on the fruits of more than 30 fig species in tropical and subtropical Asia, Africa and Australia (Bhat 1994, Fujita & Tuttle 1991, Marshall & McWilliam 1982, Thomas 1984). Food transit times in frugivorous bats are relatively rapid; generally less than 30 min (Laska 1990, Tedman & Hall 1985). Several studies have demonstrated that seed germination was either enhanced or unaffected after passage through the digestive tract of bats (Figueiredo & Perin 1995, Fleming & Heithaus 1981, Lieberman & Lieberman 1986).

Slow subduction initiation forces fast ophiolite formation

2020 ◽  
Author(s):  
Mathieu Soret ◽  
Guillaume Bonnet ◽  
Philippe Agard ◽  
Kyle Larson ◽  
John Cottle ◽  
...  
Keyword(s):  
Large Scale ◽  
Time Lag ◽  
Deformation Pattern ◽  
Far Field ◽  
Common Belief ◽  
Plate Interface ◽  
Subduction Initiation ◽  
Proposed Model ◽  
Modelling Studies ◽  
The Common

<p>Metamorphic soles are m to ~500 m thick tectonic slices welded beneath most large- scale ophiolites (usually ~20 km thick). They typically show a steep inverted metamorphic structure where the pressure and temperature (T) conditions of crystallization increase upward, from the base of the sole (500 ± 100°C at 0.5 ± 0.2 GPa) to the contact with the overlying peridotite (800 ± 100°C at 1.0 ± 0.2 GPa). The inverted  T gradient was historically interpreted as a result of heat transfer from the incipient mantle wedge toward the nascent slab synchronously with the overlying ophiolite formation (within only 1-2 Myrs). Their mineralogical assemblage and deformation pattern provide major constraints on the nature and the timing of the processes controlling the dynamics of the plate interface during early subduction.</p><p>Soret et al. (2017, 2019) recently reappraised the tectonic–petrological model for the formation of metamorphic soles below ophiolites, showing that the present-day structure of the sole results from the successive stacking of several homogeneous oceanic crustal slivers (without internal T gradient). This stacking marks the evolution of rheological properties of slab material and peridotites of the upper plate as the plate interface progressively cools (Agard et al., 2016). These findings outline the thermal and mechanical complexity of early subduction dynamics, and highlight the need for refined numerical modelling studies.</p><p>Lu-Hf geochronology on garnet from the Oman metamorphic sole has recently shown that the earliest accreted subunit, found directly against the upper plate mantle, was initially buried ≥ 8 Ma earlier than previously estimated (Guilmette et al., 2017). These results imply initiation ≥ 8 Ma before the formation of the ophiolite, which underscores the common belief that ophiolite-sole couples record spontaneous subduction initiation and rather indicates far-field forcing long before upper plate extension and mantle upwelling.</p><p>We herein present new U-Pb titanite and monazite petrochronology across the different sub-units of the Oman metamorphic sole. Our results confirm the time lag of several million years between subduction initiation and the ophiolite formation, therefore supporting the recently proposed model of far-field forced subduction initiation. They also reveal a significant time lag between the underplating and exhumation of each sub-unit of the sole.</p>

scholarly journals Lateralization When Monitoring Predators in the Wild: A Left Eye Control in the Common Wall Lizard (Podarcis muralis )

Ethology ◽  
2010 ◽  
Vol 116 (12) ◽  
pp. 1226-1233 ◽  
Author(s):  
José Martín ◽  
Pilar López ◽  
Beatrice Bonati ◽  
Davide Csermely
Keyword(s):  
Podarcis Muralis ◽  
Common Wall ◽  
In The Wild ◽  
The Common

scholarly journals Help thine enemy: the evolution of short ranging signals

2018 ◽  
Author(s):  
Szabolcs Számadó
Keyword(s):  
Theoretical Model ◽  
Short Range ◽  
Risk Model ◽  
Honest Signalling ◽  
Successful Attack ◽  
Game Theoretical Model ◽  
Soft Song ◽  
Noisy Conditions ◽  
Evolutionarily Stable

AbstractThe proximity risk model offers one possible explanation of honest signalling of aggressive intent in biology. This model assumes that the probability of successful attack is a function of the distance between the contestants and that this distance can be correctly estimated. This later assumption may not hold in nature where contestants have to estimate this distance under noisy conditions. Here I investigate with the help of a game theoretical model whether short-range ranging signals can be evolutionarily stable under such conditions. These signals can help the opponent to estimate the correct distance, thus they can promote honest signalling of intentions. Here I show that ranging signals that help the estimation of distance between opponents can be evolutionarily stable. However, such help only benefits those individuals who are able and willing to attack. As a result, ranging signals in themselves are an honest cue of proximity and in turn they are honest cues of aggressive intent. I give an example: “soft-song” in birds, and I discuss the predictions of the model.

scholarly journals Telomere length is highly heritable and independent of growth rate manipulated by temperature in field crickets

2020 ◽  
Author(s):  
Jelle Boonekamp ◽  
Rolando Rodríguez-Muñoz ◽  
Paul Hopwood ◽  
Erica Zuidersma ◽  
Ellis Mulder ◽  
...  
Keyword(s):  
Growth Rate ◽  
Telomere Length ◽  
Temperature Treatment ◽  
Field Cricket ◽  
Negative Effects ◽  
Human Infants ◽  
Apparent Lack ◽  
Telomere Attrition ◽  
In The Wild ◽  
Telomere Biology

AbstractMany organisms are capable of growing faster than they do. Restrained growth rate has functionally been explained by negative effects on lifespan of accelerated growth. However, the underlying mechanisms remain elusive. Telomere attrition has been proposed as a causal agent and has been studied in endothermic vertebrates. We established that telomeres exist as chromosomal-ends in a model insect, the field cricket, using terminal restriction fragment and Bal 31 methods. Telomeres comprised TTAGGn repeats of 38kb on average, more than four times longer than the telomeres of human infants. Bal 31 assays confirmed that telomeric repeats were located at the chromosome-ends. We tested whether rapid growth is achieved at the expense of telomere length by comparing crickets reared at 23°C with their siblings reared at 28°C, which grew three times faster. Surprisingly, neither temperature treatment nor age affected average telomere length. Concomitantly, the broad sense heritability of telomere length was remarkably high at ~100%. Despite high heritability, the evolvability (a mean standardized measure of genetic variance) was low relative to that of body mass. We discuss the different interpretations of these scaling methods in the context of telomere evolution. It is clear that some important features of vertebrate telomere biology are evident in an insect species dating back to the Triassic, but also that there are some striking differences. The apparent lack of an effect of growth rate and the total number of cell divisions on telomere length is puzzling, suggesting that telomere length could be actively maintained during the growth phase. Whether such maintenance of telomere length is adaptive remains elusive and requires further study investigating the links with fitness in the wild.

scholarly journals The emergence of cooperation by evolutionary generalization

2021 ◽  
Vol 288 (1951) ◽  
pp. 20210338
Author(s):  
Félix Geoffroy ◽  
Jean-Baptiste André
Keyword(s):  
Machine Learning ◽  
Evolutionary Model ◽  
Machine Learning Techniques ◽  
Cooperative Behaviour ◽  
Human Species ◽  
Learning Techniques ◽  
In The Wild ◽  
Emergence Of Cooperation ◽  
Evolutionary Analogy ◽  
Evolutionarily Stable

In principle, any cooperative behaviour can be evolutionarily stable as long as it is incentivized by a reward from the beneficiary, a mechanism that has been called reciprocal cooperation. However, what makes this mechanism so powerful also has an evolutionary downside. Reciprocal cooperation faces a chicken-and-egg problem of the same kind as communication: it requires two functions to evolve at the same time—cooperation and response to cooperation. As a result, it can only emerge if one side first evolves for another reason, and is then recycled into a reciprocal function. Developing an evolutionary model in which we make use of machine learning techniques, we show that this occurs if the fact to cooperate and reward others’ cooperation become general abilities that extend beyond the set of contexts for which they have initially been selected. Drawing on an evolutionary analogy with the concept of generalization, we identify the conditions necessary for this to happen. This allows us to understand the peculiar distribution of reciprocal cooperation in the wild, virtually absent in most species—or limited to situations where individuals have partially overlapping interests, but pervasive in the human species.

Allosuckling in a captive group of wild cavies Cavia aperea

Mammalia ◽  
2018 ◽  
Vol 82 (4) ◽  
pp. 355-359
Author(s):  
Patrícia Ferreira Monticelli ◽  
Rosana Suemi Tokumaru ◽  
César Ades
Keyword(s):  
Social Structure ◽  
The Other ◽  
Common Occurrence ◽  
Captive Group ◽  
In The Wild ◽  
The Common ◽  
Cavia Aperea ◽  
Rare Opportunity

AbstractWe took the rare opportunity to observe and quantify spontaneous allosuckling in a captive group ofCavia apereacaptured in the wild (a male, two females and their offspring). We recorded behavior interactions between all offspring and each of the adults between days 6 and 20 of life. Infants suckled equally from their mother and from the other female, which differs from a previous report in which mothers typically nursed own young. In addition, infants stayed closer to the other female than to mother or to the father. We discuss these results in the light of the common occurrence of allosuckling in Cavioidea and social structure.

scholarly journals Behavioural and physiological responses of birds to environmentally relevant concentrations of an antidepressant

2014 ◽  
Vol 369 (1656) ◽  
pp. 20130575 ◽  
Author(s):  
Tom G. Bean ◽  
Alistair B. A. Boxall ◽  
Julie Lane ◽  
Katherine A. Herborn ◽  
Stéphane Pietravalle ◽  
...  
Keyword(s):  
Wastewater Treatment Plants ◽  
Physiological Responses ◽  
Individual Variability ◽  
Control Treatment ◽  
Activity Levels ◽  
Wildlife Species ◽  
Contaminated Food ◽  
In The Wild ◽  
Exposure Levels ◽  
The Common

Many wildlife species forage on sewage-contaminated food, for example, at wastewater treatment plants and on fields fertilized with sewage sludge. The resultant exposure to human pharmaceuticals remains poorly studied for terrestrial species. On the basis of predicted exposure levels in the wild, we administered the common antidepressant fluoxetine (FLUOX) or control treatment via prey to wild-caught starlings ( Sturnus vulgaris ) for 22 weeks over winter. To investigate responses to fluoxetine, birds were moved from their group aviaries into individual cages for 2 days. Boldness, exploration and activity levels showed no treatment effects but controls and FLUOX birds habituated differently to isolation in terms of the concentration of corticosterone (CORT) metabolites in faeces. The controls that excreted higher concentrations of CORT metabolites on day 1 lost more body mass by day 2 of isolation than those which excreted lower levels of CORT metabolites. CORT metabolites and mass loss were unrelated in FLUOX birds. When we investigated the movements of birds in their group aviaries, we found the controls made a higher frequency of visits to food trays than FLUOX birds around the important foraging periods of sunrise and sunset, as is optimal for wintering birds. Although individual variability makes interpreting the sub-lethal endpoints measured challenging, our data suggest that fluoxetine at environmentally relevant concentrations can significantly alter behaviour and physiology.

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