Related Experiment Video
Updated: Jul 14, 2026
08:59
The Other End of the Leash: An Experimental Test to Analyze How Owners Interact with Their Pet Dogs
Published on: October 13, 2017
Cope's rule, hypercarnivory, and extinction in North American canids
Blaire Van Valkenburgh1, Xiaoming Wang, John Damuth
1Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA 90095-1606, USA. bvanval@ucla.edu
Science (New York, N.Y.)
|October 2, 2004
Summary
Large carnivorous mammals face extinction due to selection for larger size, leading to hypercarnivory and increased vulnerability. This evolutionary path, driven by energetic constraints, ultimately caused clade failure in extinct North American canids.
Area of Science:
- Paleontology
- Evolutionary Biology
- Mammalian Ecology
Background:
- Successive clades of large carnivorous mammals have diversified and gone extinct over the past 50 million years.
- The causes of these extinctions are often poorly understood.
- Cope's rule describes the pervasive selection for larger body size in many evolutionary lineages.
Purpose of the Study:
- To investigate the link between selection for larger size, dietary specialization, and extinction risk in large carnivorous mammals.
- To test the hypothesis that energetic constraints and hypercarnivory increase extinction vulnerability.
Main Methods:
- Analysis of two major clades of extinct North American canids.
- Examination of evolutionary trends in body size and diet.
- Correlation of dietary shifts with species durations and extinction patterns.
Main Results:
- Evolution of larger size in these canid clades was associated with a dietary shift towards hypercarnivory.
- Increased hypercarnivory correlated with a decline in species durations.
- Species with more specialized diets exhibited shorter durations.
Conclusions:
- Selection for larger size (Cope's rule) in carnivores can lead to hypercarnivory and increased extinction vulnerability.
- Attributes promoting individual success (larger size) can result in progressive evolutionary failure of clades.
- Energetic constraints play a crucial role in the extinction dynamics of large carnivores.
Related Concept Videos
01:38Limits to Natural Selection
Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.For one, natural selection can only act upon existing genetic variation. Hypothetically, redtusks may enhance elephant survival by deterring ivory-seeking poachers. However, if there are no gene variants—or alleles—for redtusks, natural selection cannot increase the prevalence of...
02:59Animal Mitochondrial Genetics
Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...
02:41Lethal Alleles
Agouti: A Lethal Allele
Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is responsible for the color of the coat in mice. This gene codes for an agouti-signaling protein, which is responsible for melanin distribution in mammals. The wild-type allele gives rise to gray-brown coat color in mice, while the mutant allele gives rise to yellow coat color. In addition to coat color, the agouti gene is associated with the yellow...
Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is responsible for the color of the coat in mice. This gene codes for an agouti-signaling protein, which is responsible for melanin distribution in mammals. The wild-type allele gives rise to gray-brown coat color in mice, while the mutant allele gives rise to yellow coat color. In addition to coat color, the agouti gene is associated with the yellow...
01:30Apoptosis
Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
01:18Autophagic Cell Death
Christian de Duve discovered “autophagy,” a process in which cellular components are engulfed by membrane-bound organelles called autophagosomes. The autophagosomes then fuse with lysosomes to digest the enclosed contents. Autophagy is generally activated in cells to prevent cell death. However, cell death is triggered when the damage is beyond repair.
Autophagy and Apoptosis
Autophagy can activate apoptosis. In normal conditions, the autophagy activating protein Beclin-1 and pro-apoptotic...
Autophagy and Apoptosis
Autophagy can activate apoptosis. In normal conditions, the autophagy activating protein Beclin-1 and pro-apoptotic...
01:24Generalization, Discrimination, and Extinction
Generalization, discrimination, and extinction are key concepts in operant conditioning that influence how behaviors are learned and maintained.
Generalization occurs when a behavior reinforced in one context is performed in similar situations. For instance, a student who studies diligently for calculus and receives excellent grades might apply the same study habits to psychology and history, expecting similar results. Generalization shows how learning in one setting can influence behavior in...
Generalization occurs when a behavior reinforced in one context is performed in similar situations. For instance, a student who studies diligently for calculus and receives excellent grades might apply the same study habits to psychology and history, expecting similar results. Generalization shows how learning in one setting can influence behavior in...