The differences in marsupial’s semelparity

Big-bang  reproductive strategy is  called  semelparity which is  a process by which  animals invest  in  a  mating  season  and  dies   afterwards.  This  occurs in  small marsupials terrestrial  mammals  which  have  two  distinct groups- the  Dasyuridae and  the  Didephidae. The D hallucatus are the male northern quolls which are large marsupials.  They weigh more than a kilo. The large marsupials are known to die after their first season of mating.For the female Dasyridae have single oestrus   during the winter which are highly synchronized. Their  male  counterparts  totally commit  themselves to this  mating  time at  the  expense of  future  mating  attempts.  The  two  groups  of  small  marsupials  terrestrial  mammals  of  the  males  have  high  levels  of  stress hormones  known as  corticosteroids during the  mating rut.  The  hormones  makes body  proteins  to be  broken down  so  that  energy  can   be produced.  This  means  that  the  small,  size  marsupials  which  weigh  approximately  3000g  cannot  lay  down  enough  energy reserve  in  body  fat   form.

This is  made  worse  by the  fact  they  there  is  always  food  shortage during  winter. These males  can  survive  long enough  to mate  but will  undergo  psychological   consequences  , impaired  immune  systems, decline  of  the general  body condition and inflammatory  system.  They also experience gastrointestinal ulceration which ultimately kills them.The Semelparity in D. Hallucatus differs from the small size marsupials terrestrial mammals.  The males have larger fat storage in their tails. They do not experience gastrointestinal ulcers and raised corticosteroid concentration. However,  after  breeding  they too  experience  poor body condition with increased testosterone  levels  just  like  the  semelparous  marsupial  mouse- the  Antechina Struartii.  These species however survive more than one breeding.  The semelparity in marsupials is controlled by sex hormone – the testosterone.  This  therefore  explains  that  the  break  down of protein is  as a  secondary modification as a result of high  level of  stress hormone.  This is a primary process in mammalian semelparity.

Large  marsupials  are faced  with  developmental  constrain  that is  unexplainable which is the  mental  constraint  that  predisposed  to  semelparity evolution.  A  comparative analysis  is  needed  to  explain  this phenomena to  determine difference of   the  marsupial  to  other  mammalian groups.has  been  found  that in  small  selparous  marsupials,  the  reproduction  of  sperms  fails  shortly  before  mating which is  a  condition  that  does not happen in D.hallucatus (Oakwood,2001, p 407). With  the  explanation of  semalparous marsupials  dieing  immediately  after mating, it is  understandable  and  logical but  the  fact  that  in  D.halucatus,  sperm  production is   still maintained  during  rutting  seasons in  unknown.  It is  therefore unexplainable  to  know  why  the  male  die after mating and in relation to this, it  explains  why  the  female  northern  quoll  have  minimal  reproduction of the  young after their first year .have  a  duty  to explain the  deleterious  mutation  that  acts  after  breeding  of a these  species, and  also  how  to connect these  findings with the existing  theories  of  evolution  of  life  history  of  mammals. This  could  explain  the  adaptation of  a  scientific  element  that  has not been  identified in the  environment  or circumstances in the ecological  system  with  unknown effect  to the  marsupials group.

Reference

Oakwood, M, Bradley, A and Cockburn, (2001) A ProcvRSopc Land B, p 407

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