Which of the following is essential (needed) for natural selection to occur? equal survival rates for all offspring
dramatic or major environmental changes
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genetic variation in species
there is no competition between species

1 and 6 for apex

many phylogenetic trees have a single lineage at the base representing a common ancestor. a lineage that evolved early from the root and remains unbranched is called basal taxon. when two lineages stem from the same branch point, they are called sister taxa.

can i get the brainliest pls

explanation: