Jose Climent1,2, Luis Santos del Blanco2, Luis Sampedro3, Rafael Zas3, Ricardo AlÃa1,2. 1 Forest Ecology and Genetics, CIFOR-INIA, Madrid 2 Sustainable ...
Life history trade-offs and human-driven microevolution in Maritime pine, a managed forest tree
Instituto Universitario de Investigación GESTIÓN FORESTAL SOSTENIBLE Universidad de Valladolid-INIA
Jose Climent1,2, Luis Santos del Blanco2, Luis Sampedro3, Rafael Zas3, Ricardo Alía1,2 1
Forest Ecology and Genetics, CIFOR-INIA, Madrid
2
Sustainable Forest Research Institiute, Uva-INIA 3 Misión Biológica de Galicia-CSIC
BACKGROUND • Trees are massive organisms, with high maintenance costs, long lifespan, delayed reproduction and long life cycles. As any other organism, they must cope with different environments by finely tuning their relative allocation of resources to growth, reproduction and maintenance. • Forest trees typically harbor high levels of additive genetic diversity both between and within populations (1) • Forests -and hence forest trees- are facing new challenges due to climate warming and other human-derived impacts like forest fires. • Under this scenario, selection for earlier and enhanced reproduction is predicted by life history theory in natural, largely undomesticated populations (2), but forest management, particularly tree breeding, can also modify and even counteract these adaptive selective pressures. HYPOTHESES • Due to evolutionary trade-offs (costs of reproduction and costs of defense mechanisms), man-made selection aimed at fast growth and straight stems, should derive in less resources devoted to alternative processes, conducive to delayed reproduction and/or lower resistance to herbivory.
Figure 1: Typical pine phenotype selected for in both experiments
METHODS
Figure 2: Area of selection for Experiment 1 (dark green) and reproductive features observed in the field trial
Hylobius abietis
Two independent field progeny tests of Maritime pine, comparing halfsib progenies from mothers selected for higher growth and straight stem with thin branches -aimed at enhanced timber yield (Fig 1) with an unselected control seed lot: • EXPERIMENT 1 (Fig 2, Iberian Range, NE Spain) evaluated at 8 and 11 years including both growth and female and male reproduction (cone counts) at the onset of reproductive stage. N = 31 families from the same population (3). • EXPERIMENT 2 (Fig 3, Galicia, NW Spain) evaluated at 3 years, including diameter growth and damage from pine weevil (Hylobious abietis) N = 31 families from various populations (4, 5).
Figure 3. Resistance to herbivory, Experiment 2: pine weevil and damages observed in the field trial
RESULTS EXPERIMENT 1: Delayed reproduction
EXPERIMENT 2: Lower resistance to insect herbivory 11
Selected families
C Unselected seed lot
Increase of threshold height for reproduction
Diameter growth (mm))
S Selected families 10
9
8
Unselected seed lot 7 5
10
15
20
25
Tolerance to H. abietis herbivory (inverse of affected stem area)
Selected progenies showed a sharp delay of both female and male reproduction, (p
