Seed predation increases from the Arctic to the Equator and from high to low elevations.

Species interactions have long been predicted to increase in intensity toward the tropics and low elevations because of gradients in climate, productivity, or biodiversity. Despite their importance for understanding global ecological and evolutionary processes, plant-animal interaction gradients are particularly difficult to test systematically across large geographic gradients, and evidence from smaller, disparate studies is inconclusive. By systematically measuring postdispersal seed predation using 6995 standardized seed depots along 18 mountains in the Pacific cordillera, we found that seed predation increases by 17% from the Arctic to the Equator and by 17% from 4000 meters above sea level to sea level. Clines in total predation, likely driven by invertebrates, were consistent across treeline ecotones and within continuous forest and were better explained by climate seasonality than by productivity, biodiversity, or latitude. These results suggest that species interactions play predictably greater ecological and evolutionary roles in tropical, lowland, and other less seasonal ecosystems.

Fitness declines towards range limits and local adaptation to climate affect dispersal evolution during climate-induced range shifts.

Dispersal ability will largely determine whether species track their climatic niches during climate change, a process especially important for populations at contracting (low-latitude/low-elevation) range limits that otherwise risk extinction. We investigate whether dispersal evolution at contracting range limits is facilitated by two processes that potentially enable edge populations to experience and adjust to the effects of climate deterioration before they cause extinction: (i) climate-induced fitness declines towards range limits and (ii) local adaptation to a shifting climate gradient. We simulate a species distributed continuously along a temperature gradient using a spatially explicit, individual-based model. We compare range-wide dispersal evolution during climate stability vs. directional climate change, with uniform fitness vs. fitness that declines towards range limits (RLs), and for a single climate genotype vs. multiple genotypes locally adapted to temperature. During climate stability, dispersal decreased towards RLs when fitness was uniform, but increased when fitness declined towards RLs, due to highly dispersive genotypes maintaining sink populations at RLs, increased kin selection in smaller populations, and an emergent fitness asymmetry that favoured dispersal in low-quality habitat. However, this initial dispersal advantage at low-fitness RLs did not facilitate climate tracking, as it was outweighed by an increased probability of extinction. Locally adapted genotypes benefited from staying close to their climate optima; this selected against dispersal under stable climates but for increased dispersal throughout shifting ranges, compared to cases without local adaptation. Dispersal increased at expanding RLs in most scenarios, but only increased at the range centre and contracting RLs given local adaptation to climate.

Risk factors associated with bruising in red deer at a commercial slaughter plant.

Bruising of slaughter animals has both economic and welfare implications. In order to identify potential risk factors we surveyed bruising of red deer carcasses from a single Deer Slaughter Plant (DSP) over a three year period. Downgrading due to bruising did not vary between the three years surveyed [1991, n = 21 454, 6.5% downgraded (dg); 1992, n = 22 289, 7.9% dg; 1993, n = 22 262, 6.1% dg]. From an intensive examination of one year's kill (1991) we related the incidence of bruising to various preslaughter transport, seasonal and animal variables. Bruising varied significantly with time of year, hot carcass weight, distance transported, carrier company and carcass fatness. Bruising was related to duration of lairage for some periods of the year which varied with sex. The majority of bruising was on one or other hindquarter implying a consistent cause of the damage. Carcass quality and deer welfare can be best protected by careful driving, by only transporting animals in good condition and avoiding transporting males during the rut.