The evolutionary relationships and taxonomy of the European hares are controversial and most of this controversy is centered on the Iberian Peninsula. Two of the six European species are endemic to this region: the Iberian hare, Lepus granatensis, and the broom hare, L. castroviejoi. While the latter is restricted to the Cantabrian mountains, the Iberian hare inhabits almost the entire peninsula, except the Northeast, which is occupied by the brown hare, L. europaeus. The Iberian hare is an important local game species and a prey of some endangered predators. Information on several aspects of its biology, including genetic characteristics and reproductive patterns are scarce, limiting the ability to establish sound management strategies. Therefore, the major goals established for this work were to study the genetic variation and reproductive biology of the Iberian hare. To achieve these goals we: a) evaluated the phylogenetic relationships within the genus Lepus, b) assessed the genetic diversity and population differentiation across its range; c) studied the seasonal variation of the breeding activity; d) estimated basic reproductive parameters, and e) analysed the influence of environmental factors on its reproductive activity.

The phylogenetic relationships of 15 species of the genus Lepus, focusing mainly on the European taxa, were studied. Using sequence data from the mitochondrial cytochrome b and a nuclear gene, transferrin, it was reported, for the first time, the introgression of L. timidus mtDNA into L. granatensis and L. europaeus in the Iberian Peninsula, far away from the extant range distribution of L. timidus. Apart from these two species, it is possible that other hare species contain mtDNA from L. timidus. This species may have introgressed with other hares that occur within its present range, or where fossils indicate its historical presence during glacial periods. The evidence that ancient introgression can occur between taxa that were once in contact but that are presently allopatric, prompt for the need of multiple loci to be used when assessing phylogenetic relationships within the genus Lepus. In the Iberian hare, L. timidus mtDNA is common in the northern part of its range. Apart from the individuals with introgressed mtDNA, all L. granatensis sequences form a well supported monophyletic group, which is also supported by the phylogenetic topology derived from the partial transferrin gene sequences. Thus, L. granatensis is clearly not related to the North African hares referred as L. capensis. The molecular data suggest that L. castroviejoi and L. corsicanus are sister taxa, which is in agreement with the published morphological data. These two species probably derive from a common ancestral form that had a wide distribution range in Europe.

The analysis of ten polymorphic protein loci revealed a relatively high genetic diversity (H_e=0.169; P=0.50 and A=2.93), suggesting that Iberian hare populations were not subjected to severe population reductions throughout their history. The low level of genetic differentiation indicated by the protein polymorphism (F_ST=0,064) suggests an absence of genetic structuring among the Iberian hare populations and, therefore, a substantial level of gene flow. Thus, the protein data conform with a scenario of panmixia for L. granatensis, which is similar to the pattern previously described for L. europaeus and L. timidus. In contrast, the analysis of mtDNA variation suggests a certain degree of population structure. The different scenarios shown by nuclear and mitochondrial markers may be due to the phylopatric behaviour of females.

Individual heterozygosity (inferred from protein loci) did not correlate with the respective fluctuating asymmetry levels in any of the three studied morphological character systems (15 epigenetic dental characters, 10 non-metric skull traits, six metric skull variables). However, a trend towards a negative relation between metric fluctuating asymmetry and heterozygosity suggests that there might be a slight positive influence of heterozygosity on developmental stability of the morphometric system that could be masked by various seasonal exogenic factors.

The study of an Iberian hare population in southern Portugal, from mid 1997 through December 1999, showed pregnant females and sexually active males in all samples, indicating that there was reproductive activity throughout the year. Mean litter size, based on the number of embryos, was 1.56 ± 0.10 (range between 1 and 4). This reproductive pattern was different from the one observed in other European hares, namely L. europaeus and L. timidus, but it was similar to that of L. capensis from Africa. However, the estimated annual potential production of young (9.8) was similar to those observed in other hare species. Our data also confirmed that there was testicular activity in males with intra-abdominal testes. Pre-natal mortality (due to loss of ova and resorption of embryos) in pregnant females with at least one embryo was 21%, and the proportion of pregnant females with pre-natal mortality was 26%. The environmental factors seem to have little effect on the Iberian hare reproduction, and only the variation of male reproductive characteristics could be explained by the climatic variables (minimum and maximum temperatures, and day length) and vegetation biomass. The higher regression coefficients were obtained when considering the precedent two-month period. These results suggest that the onset and duration of the breeding season did not depend on a single major factor (such as day length). Rather, a combination of variables (climatic, ecological and genetic) interact to influence the reproductive activity of this species.