Peter Breslin

Peter Breslin

Dec 11, 2017

Group 6 Copy 150
2

Quick Trip, Tons of Data

This was by far the shortest trip to visit the study site in Bahía Magdalena and return home in the history of this PhD project. I left Saturday, 12/2, and was back in the US by Saturday, 12/9. Come to think of it, this was the shortest trip I have ever taken to Baja.

The two main tasks were crucial, however-- to download the climate data from the EL USB data loggers in the field, and get tissue for the last taxon not sampled and not available in cultivation, Mammillaria petrophila. Downloading the climate data from the field meant actually going out to Isla Magdalena, even though I was only there for about 3 hours, as opposed to my usual 8-10 day research trips.

The bayside and ridgetop data loggers had all the readings, fortunately, although it took me a while to find the ridgetop device, as it had been carried off by a pack rat. I went to where I had left it and it was missing, and, from prior experience, I knew to go to the nearest pack rat midden and look for it. Lo and behold, there it was, left just outside (fortunately) inside a little natural pile of rocks, about 100 m from where I had left it.

The small scale climate data, particularly from the sharply contrasted bayside versus ridgetop habitats, will prove essential for developing the habitat suitability models. Climate data generally can only be interpolated down to the 800 m scale, and the more interpolation you do, the more error your generate. This real time local data that I've collected will make very small scale modeling possible.

Compare the bayside and "Logger 3" (ridgetop) climate data-- I couldn't have hoped for more clear distinction. In particular, look at temperature (the orange colored values) versus relative humidity (the blue colored values). As I suspected, the relative humidity of the ridgetops is noticeably higher, consistently. In fact, the average for this time period for the bayside habitat is 46% and for the ridgetops, it's 68%. I expect this dramatic difference to offer strong insight into the habitat suitability of the species I am studying. Ridgetop populations are dense, extensive and show a much higher rate of recruitment of new individuals. In fact, preliminary matrix population models show an extinction curve for bayside populations over the next 50 years under current conditions, but flourishing for the ridgetop populations. It will be particularly important to factor in the possible effects of climate change on the fog regime for the ridgetops.

The other important goal of this brief trip was getting tissue of Mammillaria petrophila, a somewhat challenging plant to sample, as it is only known from about 700 m elevation and higher, in the Sierra la Laguna of Baja California Sur.

Mammillaria petrophila

After a 3 hour hike up into the Sierra, I finally located one individual. The species is similar to the globular, lactiferous (that is, producing a white milky latex that flows when the tissue is cut) Mammillaria of Baja, Sonora and Arizona-- M. brandegeei, M. peninsularis, M. johnstonii, M. heyderi and M. macdougalii.

In prior molecular phylogenies, these globular species have consistently fallen out into a different clade than the more diverse group of species of the same region that have hooked spines. It will be interesting to see if these species have a probable different biogeography and evolutionary history from the other species I am including in the molecular phylogeny project.

Anyway, sometimes one gets a lot done in a short amount of time. That was the case this trip. In May, I expect to be in the field for my usual 4 to 5 weeks.

2 comments

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  • Richard Malcolm
    Richard MalcolmBacker
    And don't overload your car. It wasn't designed for tons of data.
    Dec 12, 2017
  • Richard Malcolm
    Richard MalcolmBacker
    Congrats. And I love the anthropomorphic language.
    Dec 12, 2017

About This Project

I am developing and applying innovative population genetics data analysis with habitat suitability modeling to solve longstanding challenges in the effort to save endangered plant species. Combining high throughput RADseq data analysis with species distribution models, I am exploring relatively inexpensive, feasible methods to generate powerful population viability assessments, estimates of threshold population size and the constraints on the habitats of rare plants.

Blast off!

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