Santa clara valley dudleya (dudleya setchellii SYN

The U.S. Fish and Wildlife Service, Region 8, awarded a $367,053 Project Grant under the Central Valley Project Improvement Act (CVPIA) program (CFDA 15.648) to President And Board Of Trustees Of Santa Clara College. The grant supports research to examine the distribution of genetic diversity within and among the threatened Santa Clara Valley dudleya plant populations. Key research activities include:

• Assessing clonal reproduction and gene flow using next-generation DNA sequencing
• Quantifying pollinator identity, frequency, and pollen movement
• Evaluating seed dispersal by wind and its impact on habitat occupancy
• Metapopulation modeling to inform conservation and reestablishment strategies
• Experimentally testing propagation techniques and wild seeding for restoration

This research aims to provide essential insights to support the effective conservation and recovery of the federally endangered Santa Clara Valley dudleya, a narrowly endemic plant found only in southern Santa Clara County, California. The grant period runs from October 1, 2023 to September 30, 2026.

Dudleya abramsii SSP. Setchellii) is a federally endangered perennial succulent known only from southern santa clara county, CA. IT is a covered species in the santa clara valley habitat plan (HCP nccp). This serpentine endemic is mostly limited to rocky outcrops and serpentine barrens within serpentine grasslands (ICF 2012). With its highly restricted distribution and unique habitat requirements coupled with adjacency to the densely populated and rapidly expanding silicon valley, basic research questions need to be answered to ensure effective conservation and recovery. We propose to examine the distribution of genetic diversity within rocky outcrops, between adjacent outcrops and across the range of the known occurrences using next-generation ddrad-SEQ. These genome-wide markers will allow US to assess the degree of clonal reproduction within serpentine outcrops and the amount of gene flow (or alternatively inbreeding) among occurrences. The genetic diversity analyses will be complemented with experiments to assess the relative contributions of pollen movement and seed dispersal in controlling gene flow. We will record pollinator observations quantifying the frequency and identity of the primary pollinators and estimate pollen flow within and among rocky outcrops at three focal sites. In addition, we will determine the efficacy of gene flow by wind dispersal using seed trapping at the same three sites which will help assess why santa clara valley dudleya occurs on some rocky outcrops and not others even though they seem equally suitable. These investigations will be complemented with metapopulation modeling based on new field surveys which will be combined with data from four previous surveys spanning 10 years at focal sites. In anticipation of RE-establishing extirpated populations and eventually establishing new populations as needed (USFWS 2021B), we will experimentally test alternative propagation techniques (varying substrates) and conduct wild seeding experiments using local seeds with and without supplemental water in alternative microhabitats (with and without moss lichen associates). Anecdotally, we have observed that drought stress compounded by local fires clearly indicates that the santa clara valley dudleya does not live forever as suggested by its common name. The proposed research is essential in reaching conservation goals of understanding the degree and mechanisms of isolation and connectivity among rocky islands within these already insular serpentine grasslands.