Consider a comparison of two cladistic analyses aimed at reconstructing the phylogeny of a particular set of mammalian species. One of these studies used Y-chromosome sequences and the other used mtDNA sequences, and both studies successfully avoided the problems associated with homoplasy. Explain why the species trees estimated by these studies would likely be very similar, despite the fact that these data sets were generated by lineage histories that do not contain ANY individuals in common (Y-chromosomes evolve thru males only, while mtDNA evolves thru females only)?

Both the chromosome Y and the mtDNA represent specific lineages, it means that they can be used to reconstruct the evolutionary history by patrilineal and matrilineal relationships, respectively. Phylogeography and phylogeny are disciplines that often use both types of genomic sequences in order to avoid the problem that represents the genetic phenomenon of recombination  when tracing the evolutionary history of organisms

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.