相关实验视频

Updated: Aug 9, 2026

Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents
05:46

Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents

Published on: January 24, 2013

在脊椎动物群体中,自然的自由活动期是脊椎动物群体的自然自由活动期

C H Lowe, D S Hinds, P J Lardner

    Science (New York, N.Y.)
    |April 28, 1967
    PubMed
    概括

    "平均周期长度"方法对于研究吉拉怪物和袋鼠老鼠的昼夜节律是不可靠的. 回归分析提供了一个更精确的方法来分析这些沙漠物种的自由运行时期.

    更多相关视频

    Rodent Estrous Cycle Monitoring Utilizing Vaginal Lavage: No Such Thing As a Normal Cycle09:05

    Rodent Estrous Cycle Monitoring Utilizing Vaginal Lavage: No Such Thing As a Normal Cycle

    Published on: August 30, 2021

    A Simple and Inexpensive Running Wheel Model for Progressive Resistance Training in Mice06:59

    A Simple and Inexpensive Running Wheel Model for Progressive Resistance Training in Mice

    Published on: April 28, 2022

    相关概念视频

    Life Histories01:29

    Life Histories

    Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented by two primary reproductive strategies; K-strategists produce few offspring but provide substantial parental support, whereas r-strategists produce much progeny that receives little care. These strategies are related to an organism’s survival likelihood across its lifespan, which is represented by a survivorship curve. Three general types of...
    Energy Budgets and Reproductive Strategies00:51

    Energy Budgets and Reproductive Strategies

    Organisms must balance energy intake with the energy required for growth, maintenance, and reproduction. These trade-offs result in a variety of survivorship and reproductive strategies, including semelparity and iteroparity. Semelparous species reproduce only once in their lifetime, often investing most available resources into that single reproductive event. Iteroparous species, by contrast, reproduce multiple times over their lifetimes, typically allocating fewer resources to any single...
    Speciation Rates01:07

    Speciation Rates

    Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
    Limits to Natural Selection01:38

    Limits 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...
    Genetic Drift03:33

    Genetic Drift

    Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...
    Gene Evolution - Fast or Slow?02:05

    Gene Evolution - Fast or Slow?

    The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
    In contrast, regions which code...