More Like this

1. Age and location influence the costs of compensatory and accelerated growth in a hibernating mammal

   https://doi.org/10.1093/beheco/araa013  

   Heissenberger, Sarah; de Pinho, Gabriela Medeiros; Martin, Julien G; Blumstein, Daniel T (April 2020, Behavioral Ecology)

   Simmons, Leigh (Ed.)

   Abstract The increase of structural growth rates to compensate for a poor initial body condition, defined as compensatory growth, may have physiological costs, but little is known about its effects on individual fitness in the wild. Yellow-bellied marmots (Marmota flaviventer) are obligate hibernators and depend on fat accumulation acquired during an approximately 4-month summer to survive overwinter. We investigated the costs of survival and longevity of rapid growth in a wild population of yellow-bellied marmots. We used trapping data collected from 2002 to 2014 to calculate individual relative seasonal growth and assess its effects on longevity and annual survival of juveniles, yearlings, and adults. Sites were distributed in two main areas, down-valley and up-valley; the latter has a higher elevation and is an overall harsher environment. We found that relative seasonal growth had no effect on individual longevity or on juvenile and adult annual survival. For yearlings, the effect of relative seasonal growth on survival depended on the location: yearlings with high relative seasonal growth had lower survival if located up-valley, and higher survival if located down-valley. In conclusion, juveniles and adults do not appear to have detectable costs of rapid growth, although there are costs to yearling survival depending on environmental conditions. Substantial structural growth occurs when marmots are yearlings and our results are likely driven by the high conflicting demands of somatic growth versus maintenance at this stage. Thus, the costs of rapid growth are age and site dependent and may be seen in the short term for species facing temporal constraints on growth. 

   more » « less
2. Oral Processing Behavior in Bornean Orangutans of Different Age and Sex Classes

   Wyszynski, Sofia I; Kane, Erin E; Bakley, Tori D; Rinaldi, R; Susanto, Wahyu; Knott, Cheryl D. (November 2021, Northeastern Evolutionary Primatologists)

   Orangutan diets vary dramatically with food availability. Orangutans preferentially eat fruit when available, but due to dramatic and unpredictable fluctuations in fruit availability, orangutans often consume unripe fruit, bark, seeds, and leaves. Their robust craniodental structure suggests that they are well adapted to consume mechanically challenging foods. Since differences in jaw anatomy and body size pose physiological differences in terms of gape, exerted force, and resistance to wear and breakdown, growth and allometry likely affect an orangutan’s ability to process a mechanically challenging diet. Thus, we predict that orangutans of different ages and sexes process foods differently. Given juveniles' smaller and less powerful craniodental structure, and the time required to develop ecological competence, we hypothesized that juveniles may have more difficulty in processing foods than adults. We recorded the frequency that foods were introduced to the mouth, and chewed with different teeth (incisors, canines, and molars) in 561 feeding videos collected in Gunung Palung National Park in West Kalimantan, Borneo on wild orangutans (Pongo pygmaeus wurmbii). Videos were stratified by age and sex class and foods were categorized by type. Infants and juveniles use their canines significantly more frequently than adult females (p< 0.05) and flanged males (p< 0.05). Molar use also differed by age and sex class (F(3)=2.551, p=0.05), with juveniles chewing with their molars significantly more frequently than adult females (p=0.05). Differences in adult and juvenile oral processing profiles suggest juveniles may process some foods less efficiently than adults. 

   more » « less
3. An effective way to mark cohorts of juvenile terrestrial direct-developing frogs

   Pena-Jimenez, J.A.; Burrowes, P.A. (August 2021, Herpetology notes)

   Kaiser, Hinrich; Zagar, Anamarija; Müller, Hendrik (Ed.)

   Abstract. Marking juveniles of terrestrial direct-developing frogs is challenging because of their small size (< 18 mm) and fragility. This difficulty has limited studies on demography or population dynamics where empirical data on the survivorship of juveniles or their recruitment to adulthood are missing. In a controlled laboratory experiment, we tested the survivorship of wild-caught juvenile Eleutherodactylus coqui Thomas, 1966 to marking with a single colour visual internal elastomer (VIE) in the thigh, with and without additional ventral skin-swabbing for disease or microbiome monitoring. Results revealed 100% survival in all groups, and all juveniles remained unharmed, moved freely, and fed actively during three days after treatment, suggesting that this type of manipulation does not cause direct mortality. After 17 months of the experiment, we have recaptured 11% of the marked juveniles as adults, indicating that they can survive to recruitment age. We propose the use of a single VIE colour as a method to mark and follow date-specific cohorts of juvenile direct-developing frogs or young metamorphs until they reach older and larger age classes. This marking method can be used safely together with skin swabbing and provide valuable information for studies on population biology and age-specific response to environmental or disease stressors. 

   more » « less
4. Top-down effects from parasitoids may mediate plant defence and plant fitness

   https://doi.org/DOI: 10.1111/1365-2435.13617  

   Tan, C.-W.; Peiffer, Michelle; Ali, Jared G.; Luthe, D.S.; Felton, Gary w. (October 2020, Functional ecology)

   null (Ed.)

   1. Plants face many environmental stresses that can impact their survival, development and fitness. Insects are the most diverse, abundant and threatening herbivores in nature. As a consequence, plants produce direct chemical and physical defences to reduce herbivory. They also release volatiles to recruit natural enemies that indirectly protect them from herbivory. The recruitment of parasitic wasps can benefit plant fitness because they ultimately kill their insect hosts. 2. Recently, studies showed that parasitoids can indirectly mediate plant defences by modulating herbivore oral secretions. In addition to the direct benefits of parasitoids in terms of reducing herbivore survival, we tested if the reduction in induced defences by parasitized caterpillars compared to non-parasitized caterpillars may reduce the costs associated with defence expression. 3. We provide evidence that tomato plants treated with saliva from parasitized caterpillars have significantly higher fitness parameters including increased flower numbers (16.3%) and heavier fruit weight (13.5%), compared to plants treated with saliva from non-parasitized caterpillars. Since plants were grown without actual herbivores, the higher values for these fitness parameters were due to lower costs of induced defences and not due to reduced herbivory by parasitized caterpillars. Furthermore, the resulting seed germination time was shorter and the germination rate was higher when the maternal plants were previously exposed to parasitized herbivore treatment compared to control (non-treated) plants. 4. Overall, application of saliva did not result in transgenerational priming of offspring defence responses. However, offspring of parents exposed to caterpillar saliva had lower constitutive levels and higher induced levels of trypsin inhibitor than offspring from unexposed parents. 5. This study shows that the saliva of parasitized caterpillars can modulate plant defences and further demonstrates that the lower induction of plant defences is associated with elevated plant fitness in the absence of herbivore feeding, suggesting that induced plant defences are costly. 

   more » « less
5. Ontogeny and social context regulate the circadian activity patterns of Lake Malawi cichlids

   https://doi.org/10.1007/s00360-023-01523-3  

   Lloyd, Evan; Rastogi, Aakriti; Holtz, Niah; Aaronson, Ben; Craig_Albertson, R.; Keene, Alex_C (November 2023, Journal of Comparative Physiology B)

   Abstract Activity patterns tend to be highly stereotyped and critical for executing many different behaviors including foraging, social interactions, and predator avoidance. Differences in the circadian timing of locomotor activity and rest periods can facilitate habitat partitioning and the exploitation of novel niches. As a consequence, closely related species often display highly divergent activity patterns, suggesting that shifts from diurnal to nocturnal behavior, or vice versa, are critical for survival. In Africa’s Lake Malawi alone, there are over 500 species of cichlids, which inhabit diverse environments and exhibit extensive phenotypic variation. We have previously identified a substantial range in activity patterns across adult Lake Malawi cichlid species, from strongly diurnal to strongly nocturnal. In many species, including fishes, ecological pressures differ dramatically across life-history stages, raising the possibility that activity patterns may change over ontogeny. To determine if rest-activity patterns change across life stages, we compared the locomotor patterns of six Lake Malawi cichlid species.While total rest and activity did not change between early juvenile and adult stages, rest-activity patterns did, with juveniles displaying distinct activity rhythms that are more robust than adults. One distinct difference between juveniles and adults is the emergence of complex social behavior. To determine whether social context is required for activity rhythms, we next measured locomotor behavior in group-housed adult fish. We found that when normal social interactions were allowed, locomotor activity patterns were restored, supporting the notion that social interactions promote circadian regulation of activity in adult fish. These findings reveal a previously unidentified link between developmental stage and social interactions in the circadian timing of cichlid activity. 

   more » « less