scholarly journals A new specimen of the basal macronarian Camarasaurus (Dinosauria: Sauropoda) highlights variability and cranial allometry within the genus

2021 ◽  
Vol 19 ◽  
pp. 109-130
Author(s):  
D. Cary Woodruff ◽  
D. Ray Wilhite ◽  
Peter L. Larson ◽  
Matthew Eads
Keyword(s):  
Life History ◽  
North America ◽  
Intraspecific Variation ◽  
Interspecific Variation ◽  
Cranial Morphology ◽  
Causal Mechanism ◽  
Active Research

Camarasaurus represents one of the most common dinosaurs from North America, and certainly a contender for one of the most abundantly represented dinosaur taxa worldwide. With numerous specimens ranging the gamut of completeness and maturity, Camarasaurus would theoretically represent a neosauropodian exemplar towards better understanding intra- and interspecific variation, dimorphism, and life history development and strategies. And yet, counterintuitively, its abundance is seemingly a deterrent for active research. Herein we describe a new specimen of Camarasaurus sp. which is most notably known from a nearly complete and articulated skull. While Camarasaurus cranial material is unquestionably the most common sauropod cranial material from North America, our understanding of the total cranial morphology is limited, and largely relies on more limited and historic specimens. In addition to further illuminating the morphology and variation present in Camarasaurus crania, associated post-crania also allow for the first recognition of possible cranial allometry. The identification of this perplexing cranial allometry in several specimens indicates that it is not a singular variation. Though this analysis was not able to source the causal mechanism, factors such as taxonomy, dimorphism, or extreme intra-/intraspecific variation are all possible considerations for future analyses. The recognition of this undocumented cranial allometry further emphasizes that despite being so numerous, there is still vast gaps in our knowledge about Camarasaurus; and this analysis further echoes that the genus is in desperate need of revision.

scholarly journals Metabolic traits in brown trout (Salmo trutta) vary in response to food restriction and intrinsic factors

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Louise C Archer ◽  
Stephen A Hutton ◽  
Luke Harman ◽  
W Russell Poole ◽  
Patrick Gargan ◽  
...  
Keyword(s):  
Life History ◽  
Metabolic Rate ◽  
Intraspecific Variation ◽  
Brown Trout ◽  
Environmental Conditions ◽  
Food Restriction ◽  
Metabolic Rates ◽  
Intrinsic Factors ◽  
Metabolic Traits ◽  
Food Conditions

Abstract Metabolic rates vary hugely within and between populations, yet we know relatively little about factors causing intraspecific variation. Since metabolic rate determines the energetic cost of life, uncovering these sources of variation is important to understand and forecast responses to environmental change. Moreover, few studies have examined factors causing intraspecific variation in metabolic flexibility. We explore how extrinsic environmental conditions and intrinsic factors contribute to variation in metabolic traits in brown trout, an iconic and polymorphic species that is threatened across much of its native range. We measured metabolic traits in offspring from two wild populations that naturally show life-history variation in migratory tactics (one anadromous, i.e. sea-migratory, one non-anadromous) that we reared under either optimal food or experimental conditions of long-term food restriction (lasting between 7 and 17 months). Both populations showed decreased standard metabolic rates (SMR—baseline energy requirements) under low food conditions. The anadromous population had higher maximum metabolic rate (MMR) than the non-anadromous population, and marginally higher SMR. The MMR difference was greater than SMR and consequently aerobic scope (AS) was higher in the anadromous population. MMR and AS were both higher in males than females. The anadromous population also had higher AS under low food compared to optimal food conditions, consistent with population-specific effects of food restriction on AS. Our results suggest different components of metabolic rate can vary in their response to environmental conditions, and according to intrinsic (population-background/sex) effects. Populations might further differ in their flexibility of metabolic traits, potentially due to intrinsic factors related to life history (e.g. migratory tactics). More comparisons of populations/individuals with divergent life histories will help to reveal this. Overall, our study suggests that incorporating an understanding of metabolic trait variation and flexibility and linking this to life history and demography will improve our ability to conserve populations experiencing global change.

Life History and Behavior of the Bramble Leafhopper, Ribautiana tenerrima (H.-S.) (Homoptera: Cicadellidae)

1960 ◽  
Vol 92 (1) ◽  
pp. 10-20 ◽  
Author(s):  
J. Raine
Keyword(s):  
Life History ◽  
North America ◽  
Vancouver Island ◽  
Dry Season ◽  
Lower Fraser Valley ◽  
And Behavior ◽  
Fraser Valley

Since 1947, when the bramble leafhopper, Ribautiana tenerrima (H.-S.) (rubi Hardy, misella 13011.), was first reported in North America near Victoria, B.C., it has become a serious pest in cane fruit plantings on southern Vancouver Island and the lower Fraser Valley. Hoth nymphs and adults suck the sap from the leaves, producing a white stippling on the upper surfaces (Fig. 1). In a dry season a severe infestation causes many leaves to become curled and appear burned. The canes lack vigor and the size of the fruit is reduced. This is a report on a study of the life history and behavior of the species conducted at Victoria from 1953 to 1957.

scholarly journals Interspecific Variation in Life History Relates to Antipredator Decisions by Marine Mesopredators on Temperate Reefs

PLoS ONE ◽  
2012 ◽  
Vol 7 (6) ◽  
pp. e40083 ◽  
Author(s):  
Alejandro Frid ◽  
Jeff Marliave ◽  
Michael R. Heithaus
Keyword(s):  
Life History ◽  
Interspecific Variation ◽  
Temperate Reefs

scholarly journals Species' Life-History Traits Explain Interspecific Variation in Reservoir Competence: A Possible Mechanism Underlying the Dilution Effect

PLoS ONE ◽  
2013 ◽  
Vol 8 (1) ◽  
pp. e54341 ◽  
Author(s):  
Zheng Y. X. Huang ◽  
Willem F. de Boer ◽  
Frank van Langevelde ◽  
Valerie Olson ◽  
Tim M. Blackburn ◽  
...  
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Dilution Effect ◽  
Interspecific Variation

SYSTEMATICS OF THE TRICHADENOTECNUM ALEXANDERAE SPECIES COMPLEX (PSOCOPTERA: PSOCIDAE) BASED ON AN INVESTIGATION OF MODES OF REPRODUCTION AND MORPHOLOGY

1983 ◽  
Vol 115 (10) ◽  
pp. 1329-1354 ◽  
Author(s):  
B. W. Betz
Keyword(s):  
Life History ◽  
North America ◽  
Sibling Species ◽  
Species Complex ◽  
Morphological Analysis ◽  
Geographic Range ◽  
Eastern North America ◽  
Facultative Parthenogenesis

AbstractTrichadenotecnum alexanderae Sommerman is shown to represent one biparental (= euphrasic) species capable of facultative parthenogenesis (thelytoky) and three uniparental (= obligatorily parthenogenetic) sibling species, as determined by tests for mating, life history observations, and morphological analysis of specimens over the geographic range of the species complex. The name T. alexanderae is restricted to the biparental species because the holotype is a male. The three uniparental species are here named and described as T. castum n. sp., T. merum n. sp., and T. innuptum n. sp. The female of T. alexanderae is redescribed to allow its separation from the three uniparental species. A key to females of the species complex is supplied. All three uniparental species were derived from the biparental ancestor of T. alexanderae. Most collections of populations represented only by females consist of one or more uniparental species. Facultative parthenogenesis is shown to maintain a population of T. alexanderae through one generation only. The biparental species is found not to be restricted geographically to a relictual or peripheral range within the species complex, but to occupy a rather wide, north-temperate distribution across eastern North America.

scholarly journals Inter- and intraspecific variation in the Artibeus species complex demonstrates size and shape partitioning among species

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11777
Author(s):  
Brandon P. Hedrick
Keyword(s):  
Species Complex ◽  
Niche Partitioning ◽  
Fruit Size ◽  
Interspecific Variation ◽  
Cranial Morphology ◽  
Foraging Strategies ◽  
Shape Variation ◽  
Size And Shape ◽  
Ecological Resources ◽  
Artibeus Lituratus

Neotropical leaf-nosed bats (family Phyllostomidae) are one of the most diverse mammalian families and Artibeus spp. is one of the most speciose phyllostomid genera. In spite of their species diversity, previous work on Artibeus crania using linear morphometrics has uncovered limited interspecific variation. This dearth of shape variation suggests that differences in cranial morphology are not contributing to niche partitioning across species, many of which are often found in sympatry. Using two-dimensional geometric morphometric methods on crania from eleven species from the Artibeus species complex, the current study demonstrates substantial cranial interspecific variation, sexual size and shape dimorphism, and intraspecific geographic variation. The majority of species were shown to have a unique size and shape, which suggests that each species may be taking advantage of slightly different ecological resources. Further, both sexual size and shape dimorphism were significant in the Artibeus species complex. Male and female Artibeus are known to have sex specific foraging strategies, with males eating near their roosts and females feeding further from their roosts. The presence of cranial sexual dimorphism in the Artibeus species complex, combined with previous work showing that different fruit size and hardness is correlated with different cranial shapes in phyllostomids, indicates that the males and females may be utilizing different food resources, leading to divergent cranial morphotypes. Additional field studies will be required to confirm this emergent hypothesis. Finally, significant geographical shape variation was found in a large intraspecific sample of Artibeus lituratus crania. However, this variation was not correlated with latitude and instead may be linked to local environmental factors. Additional work on ecology and behavior in the Artibeus species complex underlying the morphological variation uncovered in this study will allow for a better understanding of how the group has reached its present diversity.

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