Niche expansion, body size, and survival in Galápagos marine iguanas

@article{Wikelski2000NicheEB,
  title={Niche expansion, body size, and survival in Gal{\'a}pagos marine iguanas},
  author={Martin Wikelski and Peter H. Wrege},
  journal={Oecologia},
  year={2000},
  volume={124},
  pages={107-115}
}
Abstract Foraging theory predicts that dietary niche breadth should expand as resource availability decreases. However, Galápagos marine iguanas often die during algae shortages (El Niños) although land plants abound where they rest and reproduce. On Seymour Norte island, a subpopulation of iguanas exhibited unique foraging behavior: they consistently included the succulent beach plant B. maritima in their diet. We investigated the consequences of land-plant feeding for body size and survival… 
ALGAL FOOD PREFERENCES AND SEASONAL FORAGING STRATEGY OF THE MARINE IGUANA, AMBLYRHYNCHUS CRISTATUS, ON SANTA CRUZ, GALÁPAGOS
TLDR
A variable “sawtooth” model is presented to explain differences in foraging duration according to seasonally varying algal abundance and temperature and to reveal algal preferences and other factors influencing diet.
SEASONAL CHANGES IN FOOD QUALITY: A PROXIMATE CUE FOR REPRODUCTIVE TIMING IN MARINE IGUANAS
TLDR
The results suggest that marine iguanas may use subtle changes in food quality and energy content associated with seasonal, but annually variable, changes in water temperature as a cue to initiate breeding.
The evolution of foraging behavior in the Galapagos marine iguana : natural and sexual selection on body size drives ecological , morphological , and behavioral specialization
TLDR
This chapter shows how the unique foraging strategy of the marine iguana is an adaptation resulting from the forces of both sexual selection, acting through their unique social system, and natural selection by a harsh and variable environment.
Sex and ontogenetic dietary shift in Pogona barbata, the Australian eastern bearded dragon
TLDR
It is suggested that the dietary switches observed are consistent with the Optimum Foraging Model, and that females continue to require higher levels of protein for reproduction than males beyond maturity, while males rely on sham aggression to defend territory during the reproductive season rather than resorting to aggressive behaviour.
Age-related shifts in the diet composition of southern elephant seals expand overall foraging niche
TLDR
Age-related differences in both species composition and size of larger prey species that probably relate to ontogenetic changes in diving ability and haul-out behaviour and prey availability are found.
Resource partitioning through oceanic segregation of foraging juvenile southern elephant seals (Mirounga leonina)
TLDR
It is suggested that modifications of haul-out timing and behavior enable them to exploit a patchy and unpredictable environment to avoid intra-specific competition for resources on land, space on beaches, and at-sea foraging areas.
Body Size, Performance and Fitness in Galapagos Marine Iguanas1
TLDR
Based on mechanistic understanding of individual performances, an evolutionary increase in maximum body size caused by global warming trends is predicted and it is shown in a common-garden experiment that body size may have a genetic component in iguanids.
The role of juvenile foraging ecology and growth in the evolution of life history strategies for southern elephant seals
TLDR
This study has followed juvenile seals as they grow and develop rapidly toward adulthood observing changes in foraging areas or strategies and associated changes in prey availability, differences in the seasonal availability of prey, changes in morphology and physiology for growth, maintenance or provisioning toward adulthood.
Tall swards and small grazers : competition, facilitation and coexistence of different-sized grazers
TLDR
The authors' results indicate that patch depletion affected foraging efficiency in the short term as daily foraging time increased with increasing depletion and the geese showed a preference for ungrazed patches, and competitive exclusion of the larger geese by the smaller geese will occur on very short swards.
Factors affecting adult body condition in the endangered northern rockhopper penguin
TLDR
The absence of long-term trends in male and female body condition suggests that the very low reproductive output and declining population since 1997 is probably not the result of environmental conditions during pre-breeding and pre-moult and necessitates further research into possible drivers during the breeding season.
...
...

References

SHOWING 1-10 OF 43 REFERENCES
ENERGY LIMITS TO BODY SIZE IN A GRAZING REPTILE, THE GALAPAGOS MARINE IGUANA
TLDR
Food abundance (length and turnover of algal swards) explained differences in adult body length and mass between islands as a result of energetic limitation and the finding that small animals outcompeted larger ones because of their higher foraging efficiency resembles the grazing succession in ungulate herbivores.
Field Energetics and Food Consumption of the Galápagos Marine Iguana, Amblyrhynchus cristatus
TLDR
The plant-eating lizards spend only about 1 h/ day foraging, so their foraging expenses are much lower than those of insectivorous lizards which forage 3.5-10 h/day, and foraging efficiency was 12.8, much higher than insectivory lizards studied to date, but similar to two other herbivorousLizards that forage on land.
Foraging Strategies of the Galapagos Marine Iguana (Amblyrhynchus Cristatus) : Adapting Behavioral Rules To Ontogenetic Size Change
TLDR
The observed age-related changes in foraging behavior can be explained by postulating a rule of the form 'forage while warm and warm up when getting inefficient at grazing', which means animals will also stop feeding should the stomach be filled before the end of the low tide cycle.
Optimal foraging of a herbivorous lizard, the green iguana in a seasonal environment.
TLDR
Reproduction in green iguanas shows an annual cycle, in which oviposition takes place at the end of the dry season, when intake is below maintenance levels, and the linear programming solutions indicate that food selection conformed to the protein maximization criterion.
Is There an Endogenous Tidal Foraging Rhythm in Marine Iguanas?
TLDR
Enclosure experiments showed that bitidal foraging rhythms of iguanas may free run in the absence of direct cues from the intertidal areas and operate independent of the light:dark cycle and social stimuli, suggesting the existence of a circatidal oscillator in marine iguana.
The mating systems of pinnipeds and marine iguanas : convergent evolution of polygyny
TLDR
It is hypothesize that marginal males, through continuous sexual harassment of females that stay outside territories, have exerted pressure towards the evolution of female gregariousness.
Structure and Function of the Digestive Tract of a Herbivorous Lizard Iguana iguana
TLDR
Contrary to previous assertions, reptiles can be as efficient herbivores as mammals.
Distributions of Galapagos Ground Finches Along An Altitudinal Gradient: The Importance of Food Supply
TLDR
Investigating the abundance, diet and food supply of ground finch species (Geospiza Gould) at different altitudes over a calendar year on Isla Pinta, Galapagos suggests that while competition may be occurring between species, variation in food supply is currently a far more important determinant of distributions on PintA.
"Ecological Release," Seasonal Variation in Food Supply, and the Hummingbird Amazilia Tobaci on Trinidad and Tobago
Resident populations of the Coppery—rumped Hummingbird, Amazilia tobaci, occupy the West Indian Islands of Trinidad and Tobago. Trinidad has 15 other hummingbird species, Tobago only 4 others. We
Lekking in marine iguanas: female grouping and male reproductive strategies
TLDR
Lekking in marine iguanas may represent a ‘hotshot’ phenomenon where small territorial males associate with large males to increase reproductive success.
...
...