Fecundity-Survival Trade-Offs and Parental Risk-Taking in Birds

Abstract

Life history theory predicts that parents should value their own survival over that of their offspring in species with a higher probability of adult survival and fewer offspring. We report that Southern Hemisphere birds have higher adult survival and smaller clutch sizes than Northern Hemisphere birds. We subsequently manipulated predation risk to adults versus offspring in 10 species that were paired between North and South America on the basis of phylogeny and ecology. As predicted, southern parents responded more strongly to reduce mortality risk to themselves even at a cost to their offspring, whereas northern parents responded more strongly to reduce risk to their offspring even at greater risk to themselves.

Seasonal and population variation in male testosterone levels in breeding orange-crowned warblers (Vermivora celata)

“…According to theory, they should invest relatively less in each reproductive effort and more so in self-maintenance and survival (Stearns, 1992;Ghalambor and Martin, 2001;Roff, 2002). We predicted that Catalina males should maintain relatively low testosterone concentrations to protect against testosterone-mediated survival costs.…”

“…Life history theory predicts that populations with low adult survival should invest heavily in each reproductive attempt and relatively less in self-maintenance, whereas populations with high adult survival should invest relatively more in self-maintenance and less in reproduction (Stearns, 1992;Ghalambor and Martin, 2001;Roff, 2002). Thus, if testosterone patterns reflect life history strategy, we expected that Alaska and Catalina Island males would exhibit different seasonal testosterone concentration profiles during breeding.…”

Linkages between the life-history evolution of tropical and temperate birds and the resistance of their cells to oxidative and non-oxidative chemical injury

“…Variation in life-history events is thought to reflect the differential allocation of resources, time and/or energy to competing life functions, largely growth, body maintenance and reproduction (Charnov, 1993;Ghalambor and Martin, 2001). Lifehistory variables are constrained within limited ecological space, lying along a 'slow-fast' life-history axis: animals that invest large quantities of resources in reproduction early in life generally die young, whereas animals that invest more resources in bodily maintenance tend to have fewer offspring and live longer (Saether, 1988;Promislow and Harvey, 1990;Ricklefs, 2000).…”

Causes of reduced clutch size in a tidal marsh endemic

“…Food limitation (Lack 1948), nest predation (Ricklefs 1970;Skutch 1949;Slagsvold 1982), adult survivorship (Moreau 1944), and climate (Ashmole 1963;Cooper et al 2005;Stoleson and Beissinger 1999) have all been purported to explain clutch size variation across latitudes and taxonomic groups, yet there is no consensus on a single theoretical model. Clutch size is influenced by a number of phylogenetic and environmental constraints (Martin 2004), whose hierarchical organization (Ghalambor and Martin 2001) should allow for clutch size predictions in specific populations. To understand the interactions between these constraints, however, it is necessary to examine multiple, phylogenetically controlled pairs of species or populations in a variety of environments (Ferretti et al 2005;Martin et al 2000).…”