[Basta-users] juvenile survival

[Luisa Fitzpatrick]

Hi everyone,

I have used Basta to model mortality curves in two populations of a lizard species. I have mark-recapture data for around 22 years with all individuals born in the lab, and then recaptured at maturity (age 2 or 3 if they survived) and every subsequent year that they reproduce (max lifespan 13 years).

My question is on how to incorporate survival from birth to maturity (or until first observation). Basta doesn't allow me to include observations before birth and I ran into issues for having birth dates with no observations present. I was thinking I could possibly use time intervals other than year. e.g. all the individuals that are born I can include as observations at age 1 month. Then instead of age 2,3,4 I can have observations at age 24, 36, 48.

As it is, I have conditioned the analyses to survival beyond age 2 to examine patterns in adult/reproductive life. This gives me mortality trajectories that start at mortality rate 0 at age 0 and shoot up, which gives the impression early mortality is low. The life table for ages 2-3 has a death rate of 0, and for ages 3-4 has a death rate of 0.002. When in fact I know from the dataset that survival rates from birth to maturity are approximately 20% and from age 2-3 are around 50%.

Does anyone have any feedback on the idea of using months instead of years or any suggestions for another way to address this issue?

Thanks in advance,

Luisa

Dr Luisa Fitzpatrick (she/her)
Postdoctoral Fellow Life History Evolution and Ageing
Behavioural and Evolutionary Ecology Research Group
University of Tasmania, Sandy Bay TAS 7005
https://beergrouputas.wordpress.com/



I acknowledge Aboriginal people as the traditional owners of this Land and respect their culture and identity which has been bound up with the Land, Sea, Waterways and Sky for generations.


This email is confidential, and is for the intended recipient only. Access, disclosure, copying, distribution, or reliance on any of it by anyone outside the intended recipient organisation is prohibited and may be a criminal offence. Please delete if obtained in error and email confirmation to the sender. The views expressed in this email are not necessarily the views of the University of Tasmania, unless clearly intended otherwise.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.r-forge.r-project.org/pipermail/basta-users/attachments/20240423/c17e9a86/attachment.htm>