In the mid-1800s, a German biologist, Carl Bergmann noticed a tendency for the individuals of bird and mammal species to be larger at higher latitudes, and he postulated that this reduced the surface-area to body volume and thus conserved heat among warm-blooded species. This \u201crule\u201d has widespread acceptance and has become known as Bergman\u2019s law.<\/p>\n
Bergman\u2019s law may also apply to global warming\u2014a mechanism selecting for smaller average size among organisms.\u00a0 Recently Laura Bosco and her coworkers have described decreases in the body size of wintering birds in Europe in the face of higher wintertime temperatures.\u00a0 Cold winters made Bergman\u2019s law more compelling, as a lower surface-area-to volume ratio made survival of larger warm-blooded species more likely.\u00a0 Now, as winters warm, that selection pressure is reduced.<\/p>\n
Changes in the size of individuals can also result from human activities.\u00a0 For deer, moose and bear, a trend toward smaller individuals may be due to greater hunting pressures\u2014the quest for the trophy specimen\u2014that has consistently removed the largest individuals from the population to hang on the hunting lodge wall. There is some indication that consistent removal of the largest individuals has affected the average size of some horned animals of Africa.<\/p>\n
Removals of the largest individuals has also driven marine fishes to smaller, average size.\u00a0 Fishermen pursue the largest individuals for economy of effort and often throw back the smaller, young individuals to rejuvenate the stock. Removal of large predators, often the most desirable table-fish, has caused the average size of individuals in the total catch to decline, as smaller prey species increase in relative number.<\/p>\n
All told, as a result of hunting pressure, intensive fishing, and warmer temperatures, we can expect the average size of most animals to decline.\u00a0 Only humans may be the exception.<\/p>\n
<\/p>\n
Bosco, L., A. Otterbeck, T. Fransson, A. Linden, M. Piha and A. Lehikoinen. 2023.\u00a0 Increasing winter temperatures explain body size decrease in winter bird populations of northern Europe\u2014but response patterns vary along the spatioclimatic gradient. Global Ecology and Biogeography doi: 10.1111\/geb.13754<\/p>\n
Coltman, W.W., P. O\u2019Donoghue, J.T. Jorgenson, J.T. Hogg, C. Strobeck, and M. Festa-Blanchet. 2003.\u00a0 Undesirable evolutionary consequences of trophy hunting.\u00a0 Nature 426: 655-658.<\/p>\n
Crosmary, W.G., A. Loveridge, N.H. Ndaimani, S. Lebel, V. Booth, S.D. Cote and H. Fritz. 2013.\u00a0 Trophy hunting in Africa: Long-term trends in antelope horn size.\u00a0 Animal Conservation 16: 648-660.<\/p>\n
Martins, I.S. and 24 others. 2023.\u00a0 Widespread shifts in body size within populations and assemblages.\u00a0 Science 3831: 10677-1071.<\/p>\n
Sand, H.K., G.R. Cederlund, and K. Danell. 1995.\u00a0 Geographic and latitudinal variation in growth patterns and adult body size of Swedish moose (Alces alces<\/em>).\u00a0 Oecologia 102: 433-442.<\/p>\n","protected":false},"excerpt":{"rendered":" as a result of hunting pressure, intensive fishing, and warmer temperatures, we can expect the average size of most animals to decline<\/p>\n","protected":false},"author":517,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[81,5,88],"tags":[806,803,805,804],"coauthors":[6],"class_list":["post-2468","post","type-post","status-publish","format-standard","hentry","category-climate","category-faculty","category-marine-studies","tag-bergmans-law","tag-body-size","tag-fishing-pressure","tag-hunting-pressure"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5KxUl-DO","post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts\/2468","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/users\/517"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/comments?post=2468"}],"version-history":[{"count":1,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts\/2468\/revisions"}],"predecessor-version":[{"id":2469,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts\/2468\/revisions\/2469"}],"wp:attachment":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/media?parent=2468"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/categories?post=2468"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/tags?post=2468"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/coauthors?post=2468"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}