02251nas a2200229 4500008004100000245008400041210006900125300001300194490000700207520155400214653002701768653001801795653001601813653002501829653001101854653001901865100002101884700001501905700001701920700002101937856006301958 2011 eng d00aThe effect of environmental harshness on neurogenesis: a large-scale comparison0 aeffect of environmental harshness on neurogenesis a largescale c a246 -2520 v713 a

Harsh environmental conditions may produce strong selection pressure on traits, such as memory, that may enhance fitness. Enhanced memory may be crucial for survival in animals that use memory to find food and, thus, particularly important in environments where food sources may be unpredictable. For example, animals that cache and later retrieve their food may exhibit enhanced spatial memory in harsh environments compared with those in mild environments. One way that selection may enhance memory is via the hippocampus, a brain region involved in spatial memory. In a previous study, we established a positive relationship between environmental severity and hippocampal morphology in food-caching black-capped chickadees (Poecile atricapillus). Here, we expanded upon this previous work to investigate the relationship between environmental harshness and neurogenesis, a process that may support hippocampal cytoarchitecture. We report a significant and positive relationship between the degree of environmental harshness across several populations over a large geographic area and (1) the total number of immature hippocampal neurons, (2) the number of immature neurons relative to the hippocampal volume, and (3) the number of immature neurons relative to the total number of hippocampal neurons. Our results suggest that hippocampal neurogenesis may play an important role in environments where increased reliance on memory for cache recovery is critical. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 71: 246–252, 2011.

10ablack-capped chickadee10afood hoarding10ahippocampus10alatitudinal gradient10aneuron10aspatial memory1 aChancellor, L.V.1 aRoth, T.C.1 aLaDage, L.D.1 aPravosudov, V.V. uhttps://onlinelibrary.wiley.com/doi/abs/10.1002/dneu.2084702054nas a2200181 4500008004100000245008400041210006900125300001500194490000800209520144900217653001401666653001401680653001401694100001501708700001701723700002101740856011101761 2010 eng d00aLearning capabilities enhanced in harsh environments: a common garden approach0 aLearning capabilities enhanced in harsh environments a common ga a3187 -31930 v2773 aPrevious studies have suggested that the ability to inhabit harsh environments may be linked to advanced learning traits. However, it is not clear if individuals express such traits as a consequence of experiencing challenging environments or if these traits are inherited. To assess the influence of differential selection pressures on variation in aspects of cognition, we used a common garden approach to examine the response to novelty and problem-solving abilities of two populations of black-capped chickadees (Poecile atricapillus). These populations originated from the latitudinal extremes of the species's range, where we had previously demonstrated significant differences in memory and brain morphology in a multi-population study. We found that birds from the harsh northern population, where selection for cognitive abilities is expected to be high, significantly outperformed conspecifics from the mild southern population. Our results imply differences in cognitive abilities that may be inherited, as individuals from both populations were raised in and had experienced identical environmental conditions from 10 days of age. Although our data suggest an effect independent of experience, we cannot rule out maternal effects or experiences within the nest prior to day 10 with our design. Nevertheless, our results support the idea that environmental severity may be an important factor in shaping certain aspects of cognition.10abehaviour10acognition10aevolution1 aRoth, T.C.1 aLaDage, L.D.1 aPravosudov, V.V. uhttp://lter.konza.ksu.edu/content/learning-capabilities-enhanced-harsh-environments-common-garden-approach02031nas a2200133 4500008004100000245012200041210006900163300001300232490000800245520154200253100001501795700002101810856006601831 2009 eng d00aHippocampal volumes and neuron numbers increase along a gradient of environmental harshness: a large-scale comparison0 aHippocampal volumes and neuron numbers increase along a gradient a401 -4050 v2763 a

Environmental conditions may provide specific demands for memory, which in turn may affect specific brain regions responsible for memory function. For food-caching animals, in particular, spatial memory appears to be important because it may have a direct effect on fitness via the accuracy of cache retrieval. Animals living in more harsh environments should rely more on cached food, and thus theoretically should have better memory to support cache retrieval, which may be crucial for survival. Consequently, animals in harsh environments may benefit from more neurons within a larger hippocampus (Hp), a part of the brain involved in spatial memory. Here, we present the first large-scale test of the hypothesis that Hp structure is related to the severity of the environment within a single food-caching species (the black-capped chickadee, Poecile atricapillus) with a large range encompassing a great diversity of climatic conditions. Hp size in birds collected at five locations along a gradient of environmental harshness from Alaska to Kansas ranked perfectly with climatic severity. Birds from more harsh northern climates (defined by lower ambient temperature, shorter day length and more snow cover) had significantly larger Hp volumes and more Hp neurons (both relative to telencephalon volume) than those from more mild southern latitudes. Environmental pressures therefore seem capable of influencing specific brain regions independently, which may result in enhanced memory, and hence survival, in harsh climates.

1 aRoth, T.C.1 aPravosudov, V.V. uhttps://royalsocietypublishing.org/doi/10.1098/rspb.2008.118401396nas a2200133 4500008004100000245003900041210003900080300000900119490000600128520103100134100001501165700002101180856006101201 2009 eng d00aTough times call for bigger brains0 aTough times call for bigger brains a1 -30 v23 a

Memory is crucial for survival in many animals. Spatial memory in particular is important for food-caching species and may be influenced by selective pressures such as climate. The influence of climate on memory may be facilitated through the hippocampus (Hp), the part of the brain responsible in part for spatial memory. In a recent paper, we conducted the first large-scale test of the relationship between memory, the climate, and the brain in a single food-caching species, the black-capped chickadee (Poecile atricapillus). We found that birds from more harsh northern climates had significantly larger hippocampal volumes and more neurons than those from more mild southern latitudes. This work suggests that environmental pressures are capable of influencing specific brain regions, which may result in enhanced memory, and hence survival, in harsh climates. This work gives us a better understanding of how the brain responds to different environments and how animals can adapt to their environment in general.

1 aRoth, T.C.1 aPravosudov, V.V. uhttps://www.tandfonline.com/doi/abs/10.4161/cib.2.3.8099