Asap during which period did the first land vertebrates appear? a. devonian b. mississippian c. pennsylvanian d. permian

A) Devonian

Explanation:

Fourth division of the Paleozoic era, the Devonian (or Devonian) comprises the period between 416 and 354 million years ago, succeeding the Silurian and preceding the Carboniferous.

Although in this period the terrestrial environment is increasingly conducive to life, the Devonian is still known as the "age of fish". During this period, the first vertebrae, sharks, lobed-fin fish, ray-finned fish and placodermos (group of fish with armor that took the top of the food chain) emerged. Some freshwater fish developed lungs, which gave them the ability to breathe out of the water - soon the first amphibians would originate from fish with lobed fins. On the continents, however, animal life was still marked by the presence of arthropods, such as arachnids and insects.

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the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.