Demographic, developmental and life-history variation across altitude in Erysimum capitatum

Abstract

Summary1. Natural variation in life history provides the opportunity to examine its correlated population performance. Alpine systems are considered to be vulnerable to climate change as high-altitude conditions are predicted to become more similar to those at low altitude. Comparing natural populations that exhibit variation in life history across altitude can provide information on how life history may influence the demography of alpine plants under a range of altitudinally or climatically variable conditions. 2. We compared the abundance, demography, life history and morphological development of Erysimum capitatum populations in alpine and lower-altitude habitats in the Colorado Rocky Mountains. 3. Mortality of all life stages was higher at lower elevation than in alpine sites, and low-elevation plants reproduced more quickly and expressed a semelparous life history more frequently than did alpine plants. Significant variation in post-reproductive survival, i.e. the opportunity for iteroparity, was also found across regions. 4. Several life stages contributed comparably to projected population growth in high-altitude, iteroparous populations, whereas low-elevation semelparous populations depended primarily on seedling recruitment and rapid reproductive maturation for population maintenance. Populations with intermediate levels of iteroparity differed from each other in their demography, suggesting that transitional states between iteroparity and semelparity are unpredictable. 5. Morphological development also differed between iteroparous and semelparous plants, with iteroparous plants producing more vegetative rosettes and maintaining those rosettes in a vegetative state more frequently than semelparous plants. Sites with lower soil water content were more semelparous. 6. Synthesis. These combined results suggest that changes in developmental rates and morphology may promote changes in fundamental life history. Altitudinal variation in morphology and parity is strongly associated with demographic variation across altitude, indicating that plastic or evolutionary changes in these traits would influence population performance across altitudinally or climatically variable conditions.

Life-History Responses to the Altitudinal Gradient

“…In general terms, this implies that the successful establishment ex-novo of new genets (independent physiological units, or clonal colonies, sensu Watson and Casper 1984) is infrequent. However, these paradigms regarding alpine plants are currently changing and seedling establishment may be more common and successful than previously thought (Jolls and Bock 1983;Chambers et al 1990;Forbis 2003, Forbis andDoak 2004;Giménez-Benavides et al 2007;Venn and Morgan 2009;Kim and Donohue 2011).…”

“…When comparing demography and life-history traits of populations of Erysimun capitatum from alpine and low-elevation populations, Kim and Donohue (2011) found that mortality of all life stages was higher at lower elevations than at an alpine site. At the same time, they found that low-elevation plants reproduced more quickly and were more frequently semelparous than alpine plants.…”

Variation in the reproductive success of a narrow endemic plant: Effects of geographical distribution, abiotic conditions and pollinator community composition

“…Pollen limitation is often associated with low pollinator abundance (Cosacov et al 2008;González-Varo et al 2009;Gómez et al 2010), and different pollinator species usually differ in pollinating effectiveness and may thus have different effects on plant fitness (Klein, Steffan-Dewenter, Buchori, & Tscharntke 2002;Gómez, Bosch, Perfectti, Fernández, & Abdelaziz 2007;Perfectti, Gómez, & Bosch 2009). Additionally, some habitat characteristics such as plant population size, habitat fragmentation, co-occurring flower composition, and altitude can influence plant reproduction either directly or indirectly via their effect on biotic interactions (González-Varo et al 2009;Kim & Donohue 2011). Understanding how these biotic and abiotic variables affect different phases of the reproductive cycle is essential to interpret the reproduction dynamics, geographical structure and conservation status of a plant species (Colas et al 2001;Metz et al 2010).…”

“…That is, the relative contribution of the different phases of the life cycle to the plant's reproductive output may vary spatially depending on the locally prevailing biotic interactions and abiotic conditions (Stevens, Bunker, Schnitzer, & Carson 2004;Kim & Donohue 2011). Pollinator abundance, composition and diversity have often been related to plant reproductive success (Steffan-Dewenter et al 2001;Cosacov, Naretto, & Cocucci 2008;González-Varo, Arroyo, & Aparicio 2009;Gómez, Abdelaziz, Lorite, Muñoz-Pajares, & Perfectti 2010).…”

Variation in Adaptive Traits of an Endemic Meconopsis napaulensis DC. along an Elevation Gradient in Alpine Himalaya, Central Nepal

“…When comparing plant populations growing on lower elevation areas with that of higher elevation, an obvious adaptation of high altitude plants to the adverse environment is found to be in the reduced size (Jenny-Lips, 1948;Körner, 2003). Plant species growing along the elevation gradient show considerable variations in life history strategies, including the structure of their populations and demography (Kim and Donohue, 2011). Studies pertaining to variations in adaptive traits along the elevation gradient may provide opportunities to examine performances of plant populations under environmental changes (Kim and Donohue, 2011).…”