Exploring Evolution in the Elfin Forest

one mile in 90 minutes led by Bob Field

Location: Elfin Forest boardwalk

10 minutes trailhead – what do you see and what are their relationships

10 minutes first stop – evolution of plant communities from cyanobacteria and green algae

10 minutes second stop – estuary overlook – co-evolution of plants and animals

10 minutes third stop – poison oak intersection

10 minutes fourth stop – estuary overlook – aquatic origins

10 minutes fifth stop – ferns and lichen in shade

10 minutes sixth stop - Elfin Forest highpoint – geophysical evolution

Principles:

“Genetic variation and environmental factors are causes of evolution and diversity of organisms.”

“Extinction of species occurs when the environment changes and the adaptive characteristics of a species are insufficient for its survival.”

“Earth processes today are similar to those that occurred in the past and slow geologic processes have large cumulative effects over long periods of time.”

Theme:

The diversity of life depends on interactions of energy and matter in the oceans, atmosphere, solid Earth, and Sun. Everything you see around the Elfin Forest changes over time - the land, sea, atmosphere, and biosphere. From daily and seasonal cycles to billions of years of physical and biological evolution, it's all about relationships and energy flows.

Sub-themes:

1. The transfer of energy by radiation and convection currents drives many processes on the Earth’s surface.

2. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment.

3. Plants inherited photosynthesis from green algae ancestors whose chloroplasts evolved by endosymbiosis from captured cyanobacteria.

4. As plants transitioned from an aquatic environment to land, they developed roots, stems, leaves, seeds, fruits, and flowers and they co-evolve with terrestrial animals.

Discussion:

Visitors can name something they see in the sea, sky, land, and life. We can discuss what things are made out of and how they are related. At each stop, we will discuss things we saw that were influenced by the ocean, directly or indirectly, or by the Sun, atmosphere, or solid Earth. The building blocks of life are cells which include molecules and metabolic processes. The building blocks of ecosystems are organisms which are often classified into five or six kingdoms. The Earth and its biosphere have been evolving for billions of years. Complexity grows when energy flows.

Eight guiding questions are common to our efforts to observe and explain the natural environment:

1. What do you see (observations and descriptions)?

2. What are natural systems made out of (composition and structure)?

3. How do natural systems work (material properties and interactions with energy)?

4. How do natural systems change over time (evolutionary processes)?

5. Where do natural systems come from (origin and/or formation from building blocks)?

6. What are the relationships between the parts of a system (interactions and/or common origins)?

7. What are the relationships between natural systems (interactions and/or common origins)?

8. How do natural systems become more complex over time (entropy decreases)?

The diversity, abundance, and distribution of life depend on the interactions of sunlight and water. We will discuss the influence of the oceans on everything you can see in the Elfin Forest and we will describe a variety of plant adaptations to seasonal change.

The north pole of the Earth’s axis of rotation is tilted directly toward the Sun today exposing the northern hemisphere to maximum peak and average sunlight. Seasonal changes influence everything you see here in the Elfin Forest. Seasonal changes depend on the amount of sunlight reaching our latitude. The ocean is the source of all water on the Earth. Water influences the weather, life, and the shape of the land. Wind and water are driven by the absorption and scattering of sunlight in the air and the water. All of the sand in the dunes under the Elfin Forest was formed and transported by wind and water.

Tides depend on the pull of the Sun and the Moon and vary during the day and during the year, affecting the lifestyles of many creatures. The variations in sunlight and moisture and the limited supply of essential nutrients like nitrates and phosphates determine which plants will do well here. The so-called “Pygmy Oaks” are the same species of Coast Live Oak seen throughout the California coast. They grow slowly in the Elfin Forest and, even though they may be 200 years old, only reach heights of twelve feet rather than fifty feet because of the limitations of the coastal dune environment. Apparently their acorns would produce a standard size oak if planted in a richer environment.

Fuchsia flower gooseberry goes completely dormant in the summer. Chamise has a dual root system – shallow and deep. Manzanita and ceanothus are well adapted to seasonal change – they become dormant in summer, thereby minimizing their need for water and nutrients. Deerweed and bush lupine are legumes like peas and have nitrogen-fixing bacteria in their root nodules. No plant can fix atmospheric nitrogen. Dudleya is a succulent – its stomata open at night to let carbon dioxide in because less water is lost when the air is cool and damp. It retains the gas until it needs it the next day for photosynthesis. The annual wildflowers flowers like poppies have a simple adaptation – they die – they don’t have to survive the summer in order to produce viable offspring the following spring.

The Elfin Forest is full of examples of plants and animals that interact to survive. Siena’s Point provides an opportunity for a close look at the estuary and the birds that depend on it. Everything you see depends on things you don’t see. Evolution is driven by cooperation and competition in ecosystems. The Elfin Forest has six interacting kingdoms: plants, animals, algae, fungus, bacteria, and archaea. Lichen is not a plant; it is a symbiotic community of fungus and algae or cyanobacteria. Plants cannot use the nitrogen in the air and cannot extract phosphate from most materials. They rely on bacteria and fungi to do these jobs. Plants came from green algae that were able to adapt to the land with the help of bacteria and fungi.

Plants have chloroplasts that convert sunlight, water, and carbon dioxide into glucose which is used for plant bodies and for storing energy for metabolic processes. The chloroplasts of their algae ancestors were acquired by endosymbiosis with cyanobacteria, which had previously ruled the world for billions of years causing the oxygen holocaust and saving the oceans from evaporating as the Sun grew brighter and hotter over time.

Plants are able to produce highly diverse offspring as a result of genetic mixing that occurs in the process of sexual reproduction. While some plants spread their pollen and their seeds with the help of the wind, many plants have formed symbiotic relationships with animals. Flowering plants co-evolved with insects and sometimes with birds and mammals. Bees and birds are important pollinators, being rewarded with nectar. Mammals are important seed dispersers, being rewarded with fruits and nuts.

How did plants and animals acquire seasonal adaptations? An individual’s inheritance influences its ability to survive and produce offspring in any particular physical and biological environment. The environment selects individual organisms based on their inherited adaptations. The environment shapes individuals, but rarely alters the inheritance of their offspring. In general, seasonal changes favor plants and animals that happened to have traits that provide survival advantages when the environment changes. The diversity of offspring insures that some individuals are genetically endowed to survive change. The ability to survive a changing environment also provides survival traits for plants and animals that are dispersed into new environments, wetter, drier, hotter, colder, nutrient poor, or whatever.