Answer:Long term drought, change of season from winter to summer, forest fire are unfavorable environmental factors which can deplete the amount of resources already available with the ecosystem. The long term drought will be a condition in which the ecosystem will suffer from non-availability of water.
Explanation:
Two criteria that would identify the three muscle tissues are myofibers and nuclei.
There are three types of muscles:
1. Skeletal-Contains many nuclei along the length of the muscle cell. The nuclei are displaced peripherally. The skeletal fibers are arranged parallel. The myofibril is composed of bands.
2. Smooth-This tissue contain spindle-shaped cells with a single central nucleus. Smooth muscle fibers are shorter than skeletal.
3. Cardiac-The fibers of cardiac muscle are not simply parallel. Cardiac muscle fibers are long cylindrical cells with one or two nuclei.
Its integral to the recombination and the genetic diversity from sexual reproduction on which natural selection can act upon. The recombination that occurs in meiosis plays an important role in the repair of genetic defects in Germ line cells.
I would go with none of the above because the other answers might describe early mammals but they also describe the mammals that we have now.......
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