Revealing an Endemic Herbivore-Palm Interaction in Remote Desert Oases of Baja California

Abstract

In the Central Desert of northern Baja California, blue fan palm populations (Brahea armata) are found as isolated oases on mountaintops and along canyons with ephemeral flow conditions. Here, the effect of the interaction between the larva of an endemic moth, Litoprosopus bajaensis, and this endemic blue fan palm was documented for the first time. We registered the phenology of palms by counting the number of shoots with flowers or fruits, assessing their damage and calculating the reproductive success per individual palm within three populations: San Pedro Martir, Cataviña, and La Libertad. Palm populations were severely impacted by this larva, causing high damage to the inflorescences. No differences were found in the number of inflorescence stems produced and damaged among study sites; but the reproductive success of palms was significantly higher in Cataviña than in the other sites during the entire sampling period, and consequently an important proportion of stems escaped from the herbivore predation. We suggest that differences among sites may be explained by the fact that Cataviña is the only alluvial canyon and can be considered an area of high nutrient uptake, resource availability, and rooting depths. In contrast the other two are bedrock canyons, where water runs intensely, sweeping away great portions of the nearby vegetation. Cataviña received the highest precipitation during the winter season of 2010 allowing a continuous production of inflorescence stems and fruits. This preliminary study reveals a new endemic interaction, it occurrence at population and regional levels, and highlights the role of desert oases as resource patches and connectivity pathways for mobile insects. Finally, it also highlights the effects of different water flow dynamics and water pulses in providing an opportunity window of escape from predation for host plant species living in desert environments.

Molecular genetic analysis of two native desert palm genera,WashingtoniaandBrahea, from the Baja California Peninsula and Guadalupe Island

“…Previous studies have examined certain aspects of the fundamental ecology of these species such as growth rates, mechanisms of seed dispersal and herbivore-plant interactions (Bullock & Heath, 2006;Franco-Vizcaino et al, 2007;Wehncke & López-Medellín, 2015;Wehncke, López-Medellín, Wall, & Ezcurra, 2013;Wehncke et al, 2010). The geographic distributions of certain species based on morphological characteristics such as stem size, leaf shape and color, fruit shape and size, have also been described (Cornett 2008;Felger & Joyal, 1999;Oberbauer, 2005;Minnich et al, 2011).…”

“…In spite of the ecological, ethno‐biological and economical importance of Washingtonia and Brahea palms, many aspects of their biology including species delimitations, genetic relationships between species and levels of intraspecific genetic diversity remain to be elucidated. Previous studies have examined certain aspects of the fundamental ecology of these species such as growth rates, mechanisms of seed dispersal and herbivore–plant interactions (Bullock & Heath, ; Franco‐Vizcaino et al., ; Wehncke & López‐Medellín, ; Wehncke, López‐Medellín, Wall, & Ezcurra, ; Wehncke et al., ). The geographic distributions of certain species based on morphological characteristics such as stem size, leaf shape and color, fruit shape and size, have also been described (Cornett ; Felger & Joyal, ; Oberbauer, ; Minnich et al., ).…”

The role of wild canids in the seed dispersal of Washingtonia robusta (Arecaceae) in Sonoran Desert oases

“…6). In addition, these occasional water pulses create positive conditions for seed germination, and soil denitrification due to increased soil moisture (Wehncke et al, 2013). It is estimated that 95% of the lower canyon water availability is from such ephemeral events (Bogan, 2017 personal communication).…”

Phylogenomics, biogeography, and evolution in the American palm genusBrahea

“…Species of Brahea occupy a wide variety of environmental conditions across the geographic range of the genus, from northern Mexico to Nicaragua, where they often represent major ecosystem structural components, especially in desert and other xeric habitats (Uhl & Dransfield, 1987; Henderson et al , 1995 ; Quero, 2000; Hodel, 2006; Dransfield, Uhl, et al , 2008; Wehncke et al , 2013). However, the biogeographic history of this clade is unknown, and likely complex, potentially having been shaped by vicariance, dispersal, and sympatric speciation across a geologically dynamic landscape (e.g.…”