INVESTIGADORES
SASSI Paola Lorena
congresos y reuniones científicas
Título:
ALTITUDINAL EFFECTS ON ENERGY ACQUISITION ABILITY IN A SMALL MAMMAL (Phyllotis xanthopygus, Rodentia: Muridae)
Autor/es:
PAOLA L. SASSI
Lugar:
Ottawa
Reunión:
Congreso; 1st Joint Congress on Evolutionary Biology; 2012
Resumen:
ALTITUDINAL
EFFECTS ON ENERGY ACQUISITION ABILITY IN A SMALL MAMMAL
(Phyllotis xanthopygus, Rodentia: Muridae)
Paola L.
Sassi Biodiversity Investigations Group
GIB, IADIZA, Mendoza - CONICET, Argentina. psassi@mendoza-conicet.gob.ar
Physiological ecology provides the framework to
study the diversity of responses of organisms to the environment. Desert
mammals have been models for different investigations in this field, in the
search for adaptive traits. This study addresses physiological traits relevant
for the ability of P. xanthopygus to acclimate to spatial and temporal
variability in the arid highlands of Argentina. This species presents a wide
distribution along the Andes Mountains. A broad temperature and rainfall
gradient affects vegetation resources, that in addition to the species small
size and herbivorous habits, imply possible trade-offs in its energetic and
nutritional balance. The objective of this study was to test for differences in
ability for acquisition of dry matter by populations of P. xanthopygus across
an altitudinal cline. Hypothesis:digestive strategies that maximize nutritional balance are favored
by natural selection. P. xanthopygus would display a plastic response in
resource-acquisition traits to face environmental variability, with high
altitude populations being more efficient. Study area: Central Andes, Mendoza,
Argentina. Individuals were collected at three sites along an altitudinal
transect: 1750, 2300, and 3100 m a.s.l. Variation in dry matter intake (DMI)
and digestibility (DMD) among 10 individuals from each altitude was analyzed.
Measurements were taken under three experimental treatments: at 25ºC when
arrived from the field, after two-month acclimation to 25ºC, and after
two-month acclimation to 16ºC. Factorial ANOVA was used to analyze data (body
weight as covariable).The results show no effect of altitude, while effects of
experimental treatment on DMI (F=29.9, d.f.=2, p<0.01) and DMD (F=6.32,
d.f.=2, p<0.01) were significant. Interactions between altitude and
treatment were significant for DMI (F=9.37, d.f.=4, p<0.01) and DMD(F=3.37,
d.f.=4, p<0.05). Altitudinal trends varied among treatments, revealing
population-specific strategies. Under the inertia of each origin sites
conditions, data suggest different compensatory responses in the species at
different altitudes. With acclimation to less challenging temperature
conditions (25ºC), intake decreased and digestibility pattern changed. After
acclimation to cold conditions (16ºC), adjustment responses were evident in mid
and low altitude populations, resulting in a completely different pattern. In
conclusion, there are at least partially fixed attributes to deal with energy
trade-offs, that vary among populations according to the site they inhabit and
could be due to local adaptation or ontogeny. In any case, the species shows a
plastic strategy covering the high variation in ecological conditions along the
altitudinal cline under study. Our results contribute to explain the great
range of distribution of P. xanthopygus, and pose it as a good model to
investigate potential responses to environmental changes.
This study was financially supported by Agencia
Nacional de Promoción Científica y Tecnológica (PICT 2010-0892, PICT 25778)
and Consejo Nacional de Investigaciones Científicas y Técnicas.